I installed a Rapido long block last year...no issues what so ever. the motor seems very strong. Come to find out my old block isn't crack, the problem was the 1 piece (batwing) exhaust manifolds. I replaced them with the 2 piece conversion and all issues cleared up. Now i just have an extra long block in my garage.
As far as the carb upgrade. All I can say is


I forgot to mention, there was one minor issue. The original block was all Standard bolts. The one I got from Rapido was mostly metric. So sorting out the engine mount bolts, starter bolt and bell housing bolts was kind of a ***** whippen but nothing a trip to Ace didn't take care of. I'm please with the Rapido motor.