Redhat,.... I've assembled and "finished" more then 25 of the Lyman GPR "kits" in the last 30 years.
Tacks is tell'n you right 'bout the "kit" and the "calibur",.... 'bout all you need is some "course-to-fine" sandpaper (even a few strokes with a wood-rasp if you got one and yore familiar with it), broken glass makes an excellent "scraper", metal files, emory-cloth, or even a "buff'n wheel and polish'n compound" (tho the metal don't NEED to be thet "slick").
I've always prefered to "draw file" the "WARNING label" off the barrel (the "originals" had no such label on'em). Prepare to look for a "longer set-screw" for the set-triggers, as the one thet comes with the rifle is on the "short side" due to "liability reasons".
You'll also need some "browning" or "blueing" to finish the barrel and all the "hardware",.... plain dish-soap and water will work for a "de-greaser".
I've always prefered "Tru-oil",.. for a stock-"finish".
Be sure to "pin" the ramrod-"tip" to the ramrod.
The average craftsman should enjoy finish'n one'a these "kits",.... I know, I always did!!
Good luck!!.... and, "HAVE FUN"!!