how big of a shot will a stock 4g63/T do safely.

How about you do a SEARCH. Every time you log in to post something, it tells you to SEARCH before you post. This has been asked about 327098565087435 times on here. Don't be lazy, do a search and read, and you will find your answer.

Regards,

Ive ran a 75 shot about maybe 10 times, but with my supporting mods I have I prefer the 35shot and only use in 3rd gear.
My 20g and 25psi and a 35 shot in 3rd gear seems to run smoother and still pull better. The 75 shot hits to hard and I get mad backfire and loose the tips on my #2 sparkplug.