The best thing about a rebuild of a fairly stock engine is the balancing. A fully balanced engine has much less stress than a non balanced one. The engine doesnt try to tear itself apart and pistons rods and cranks are far less stressed. Some guys have picked up 30 horsepower with a balancing job.
If you are in the sub 300 rear wheel horse range N/A and without N2O then you should be fine. Just dont run crazy timing and hit the rev limiter all the time.
I dont think I would worry about forging the bottom end until it blows or until you supercharge it. The more miles you put on it the more the rings will wear and it would be nice to have fresh rings and parts when you mount that blower.
Pistons start to fail when you have bad timing or fuel ratio. Rods fail with high compression, massive RPMs, and flex. The cranks can fail under high boost, horsepower, and torque, and compression. I dont think you would have much of a problem with any of this with a N/A non nitrous engine.