If you want the added insurance, go ahead and sink the money into the forged crankshaft, forged rods, etc.. and make it a bulletproof bottom end.
For daily street useage, with the occasional romp on the go pedal, I would use forged pistons, standard I beam rods, and a regular cast crank.
The only difference from a "normal" engine here would be the lower compression and a set of forged pistons.
Running a blower will create higer pressures and temps within the cylinder, and hyper-pathetic slugs are just not up to handling it like the forged ones will. Sure, they may hang in there for quite a while but trust me on this, you'd be much happier in the long run with a set of forged pistons.
The conn. rods would be nice if they were forged, but that is not really needed for a street engine. Unless you want to spend the extra money on a set of pretty H beam rods, stay with the regular old I-beam ones. H-beam rods are nice and tough, but if you are just running on the street, I'd choose to run with regular rods. Just have them magnafluxed, balanced, polished, and peened. Oh, one other thing 'bout the rods - I'd stay away from the aluminum ones. They are great for high rpm quarter mile runs, but not all that great for recreational driving type situations.
I'd also prefer the use of studs with any hi-po engine.
Another area you do not want to skimp on is the fuel pump. Get a high quality pump and make sure you mount a pressure gauge somewhere so you can keep tabs on your fuel pressure. Running forced induction is hard enough on the internals of the engine, but, one thing you don't want to happen is to starve the motor of fuel and create a lean condition. Forged pistons or not, that will destroy them faster than you can blink.
The smallblock chevy has a decent oiling system to begin with, so I'm not much on mucking with that, maybe someone else has a different idea, but I'd say to install a good pump (clearance the pickup from the pan of course) and let it be.
I'm not all that familiar with the kind of blower you are running (The 250). Without looking it up, I am guessing that it's a smaller cousin to the megacharger and the 671 though. With only a single 750 feeding it, I wouldn't worry about spending all that extra money on parts that you are not really going to need. (Now, if you were to race the beast every day, none of this would apply.)
Bottom line would be to just build up the engine like any other high po motor, keep the static compression around 8:1, and feed it a good supply of fuel.
Well, it's time for me to get going home, so, if you have any more questions, post em and I would be glad to help.
~Michael
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