I use to play with the ol blue bottle a fair bit.
If his engine is in pretty good nick, it will take more than that, but sneak up on it.
The most I ever used was a 300 shot, 200 in low gear on the hit and a 100 on the second gear change. The stock rods and crank took it, but they use to moan a bit, in the end, we went 200 + 50 and the engine loved it. That was 20 years ago now and let me tell ya, it was a big hit of gas back then.
Little ol 302 Windsor and it got it on the street, at the track.
If he has any questions, give me a yell or I think Shane has played with the giggly stuff too.
Actually, Shane's most likely more up to speed with it all, but tell ya mad to use a retard unit or he'll kill parts.