In looking at your posts I'm sure that the gun has a barrel with a fully supported chamber... If that is the case there is no even unreasonable load that is going to hurt that gun...
#1 thing to do if you are going to run bullets over 1350, which is quite easy, is get a 18-18.5# recoil spring. I run that weight in all my guns and they will function even with 9mm.
As to bullets, if you want to go with a Gold Dot HP there are two 124s...one with a deep cavity for 9mm and the other for .357 SIG. Speer loads the .357 SIG bullet in their rounds and CorBon uses the 9mm version in their .357 SIG rounds... Just depends on your beliefs... I personally prefer a faster opening bullet for self-defense and people are not made of Jello...
#2 is when reloading hot use Small Rifle Primers. The metal in the cups are thicker and take a lot more pressure.
Powders...I have mainly worked with Unique and SR4756. I heard great things about Blue Dot but never got the velocity others claimed to have. AA-9 is also supposed to be a real mover in Super.
Back to bullets. First thing you want to do is pull the barrel to check what you can get away with for length overall. As long as the round is under 1.280 they will fit in the magazine. Depending on the ojive of the bullet you may have to seat as deep as 1.200 as in the case of the Sierra JHP rounds. Every bullet is different. You also want to make sure there is enough bullet in the case to ensure good feeding and bullet retention.
Once you get what you feel is a correct round, make up 10 dummies and after putting them in the magazine SLOWLY cycle them trough the action watching to see how the bullet is interacting with the feedramp and is the case rim timing correctly slipping up under the extractor. If all that goes smooth, put them back in and rack the slide back hard and let go to see what the round does under speed. You may also want to measure the LOA to see if you are getting any bullet setback but this usually isn't very critical.
Once you have a round that will feed it is time to make up test rounds... I make up batches of 5 rounds of a certain powder weight and go up usually .3 grains at a time until I get start getting pressure signs. It is good that you have a chrono as that takes a lot of guessing out of things...
If you have a nice grips on your gun take them off and put a set of rubber on...like Pachmayer...if you blow a case web the only thing that ever gets damaged on a 1911 is the grips...don't ask me know I know this... In your case the likelihood of blowing a case web are very low...only my Kimber has a supported chamber barrel...none of my Colts do. I've blown about 6 cases since 1980...and that is well over 150K rounds fired. And almost all were on experimental rounds.
Invest in a Lee Carbide Factory Crimp die...also MGW has contracted with Lee for a special resizing die that puts fired brass back to factory specs...irons out any web bulge... Since I started using that die have had ZERO feeding issues with brass has been shot well over 20 times...
Here is the die at Midway...MGW no longer has them...
http://www.midwayusa.com/product/390353/lee-undersized-carbide-sizing-die-38-superhttp://www.midwayusa.com/product/721680/lee-carbide-factory-crimp-die-38-superAnd don't worry about ever wearing out that gun using even hot loads... A couple of my guns have way over 30K rounds of +P+ loads and will still run 3" at 50 yards.. If one can safely run 9x23 Winchester at 55K psi running a 125 at 1450 fps running Supers in the 40-45K range is a cakewalk for these guns...
As to 9x23 Winchester, if you can get a box pull the barrel and drop one in...if it fits the chamber it will run... Almost all my barrels will run them. For regular use I would have a flat bottom firing pin stop put in and run a 24# recoil spring...but for the occasion firing you are not going to hurt anything...
Some reading for U...
http://www.hipowersandhandguns.com/Corbon%2038%20Super%20Ammo%20Tests.htmhttp://www.hipowersandhandguns.com/38SuperTo9mm.htmhttp://www.38super.net/Lots of Handloading Data...
http://www.handloads.com/loaddata/d...ype=Handgun&Order=Powder&Source=http://www.k8nd.com/documents/hl38sup.pdfOne mans packin pistol...
http://www.thefreelibrary.com/Trail+gun+perfection%3a+Kimber%27s+.38+super+stainless+target+II.-a0285993666
You can PM any time you need something...
Bob