Can someone recommend a bore guide for:

1) Henry Big Boy Steel .357 Magnum

2) Marlin 336 .30-30

I'd like to be able to clean from the breech end.

I don't know about the Henry, but it is easy to remove the bolt from a Marlin 336 to clean from the breech end.

Or, you could use a coated cable and pull through brushes and patches or Remington/Bushmaster Squeeg-Es.

CDNN had the Remington/Bushmaster kits on sale for $12.99. Light weight and compact, a bit of kit worth keeping in your daypack.

J. Dewey muzzle bore guide.

I make my own out of syringe needle covers for the bore end, and the syringe itself for the chamber end. Made one just recently for my bolt action, just trim the plastic finger tabs, it slides all way back inside the bridge. Just drill center holes to get rod to fit inside tightly.

You don't need a bore guide to clean from the breach . This link is to a rod guide that is for breech . They are calling it a bore guide but that's not what it is .

https://rangerpointstore.com/marlin-henry-levergun-bore-guides

How about a .270 Win case with the base cut off?
Neck should fit into the muzzle

If you clean a lever rifle from he front you may push junk into the action . I always remove the bolt and clean from the rear , same with my Remington pumps and my AR. I haven't used a bore guide / muzzle protector in years . He needs what I posted a link to above.

I'm cleaning from the breach. I saw the guide from Ranger Point. However, it's for a 45-70 and .30-30. Wondering how the .30-30 model will fit in a .357 chamber?

You have a 30-30 so buy one for it and see if you get lucky and it also works with the .357 Henry . I knew from your first post that you were breech cleaning , that is why I recommended what I did . Seems some of the others did not read your post very closely and missed that fact or they would not be posting on muzzle guides. They work fine but don't keep you from pushing crud into the action .

I have used a Otis cleaning kit to clean lever guns from the breech for many years. Easily adaptable to different bore id's.

The extra beauty of a Marlin

Pull lever.......pull bolt & ejector spring

Clean the barrel easily

rifle bore cleaning is over rated , hunting rifle bores don`t need to be cleaned very often.

Just to close this out, I reached out to Eric at Possum Hollow. He had me measure the bolt diameter on my Henry Big Boy .357 (.680 dia.) and is making me a bore guide.

He is a good guy as well.