crazy quiestion of the year!!!!

yes the 375 weight class. keep in mind im new to racing & i ask alot of crazy quiestions from time to time, just wanting to learn as much as possible because im going to get my son to race next season also. he will be just 7 in jan. i thank its bought time to get him started!!!!
About 2500-3000 rpm and cam, carb, rod, flywheel, piston, valve springs, header, head machining, port work...

Two very different motors.
limited modified briggs differance as mentioned above and the biggest noticeable difference to the eye is the tillotson carb , remote fuel tank and fuel pump