You need to measure to do it right. Especially with non-adjustable rockers. Over time blocks get decked, heads get milled, etc. if he THINKS he put the wrong pushrods in it, then clearly they weren't what came out of it, and/or he has doubts. He also needs to add the correct preload, which is typically .020-.050. on a hyd setup
on shaft, non-adjustable rockers, this is all accomplished with the correct length pushrod. If they're adjustable, you have some fudge factor, but i'm assuming they aren't.
say it had a .060 head gasket originally, and the replacement you went with was .020, and it was decked .005, and the heads milled. you just took your lifter pre-load from the min acceptable, to the max acceptable, or beyond... you'll know when the lifters pump up and the valves kiss the pistons.
this is a smart $20 to spend... make sure your range is correct.
Hi-Tech Checking Push Rod Competition Cams 7702-1 - Pace Performance Parts