351 or 460 they have the same problem I have a 460 n use to only last me for about 4, 3, or sometimes once n always my bottom end it use to go out it was a headache having to rebuild my engine a few times every season till i did the lifter bushing mod n that fix the problem last season I to the boat out about 45 times with no problems I think Sabert79 should look into it before putting the engine together
The primary purpose of installing the lifter bore bushings in the passenger car blocks is to prevent oil pressure loss
if a lifter pops out of the bore. Short of the lifter popping out of its bore, the bushings do little for oil pressure safety in a good running engine. So if your previous rebuilt short blocks are failing in just 1, 2, or 3 trips
without popping out a lifter then you have engine rebuild issues and should look for another engine builder. On the other hand, if you mean to say that you were popping out lifters every 1, 2, or, 3 trips then you have similar issues just the same, and bushing the lifter bores
does not prevent the lifters from popping out their bores.
The most common reason for lifters popping out of their bores is over revving, resulting in a bent pushrod, resulting in a lifter getting pushed out of its bore. Over revving often happens in jet boats when the boat operator stays wide open throttle over a wake and airs out the boat (unloads the impeller) and the engine hits a hi C. That's not the engine's fault.
We've done thousands of horsepower without bushed lifter bores. The engine needs to be built right and also treated right.