I like them, too. I got my pistons from them - they had a better price than anyone else at the time.

 

Even pistons, it is not cheap to match the quality of stock pistons. Sure you can throw a $300 forged set in there BUT those are heavier than stock with thick rings, two strikes right off there.

The stock shortblock is pretty reliable up into the 400rwhp range, with a surprising number even getting up in the 420-430rwhp range. Sure some of us have spun rod bearings once getting up there but in my case I think it was poor fuel then tuning that did the harm, not the rpm or power. When I did my first heads/cam setup my fuel pump was insufficient at first and then I had some tuning troubles and ended up spinning a rod bearing. Even as I tweaked and tinkered adding more power though I never repeated that failure despite just replacing that engine with a junkyard shortblock without so much as looking at the bearings.

 

To answer your original question: I've used a few of the Scat cast steel 3.750 cranks. With the neutral balancer, and stock externally weighted flywheel/flexplate you won't need any heavy metal unless the bobweight gets around 1875 grams or above. Then it would probably need a small piece in the front counterweight.

I've never used an Eagle, so I can't offer any advice there, but I agree that your money is best invested in cylinder heads.

 

Well, I don't know if you're on a budget, but if you want a little extra kick, I recommend a 355, or even just freshen up the 350(355 if cylinders require it, id do it), throw a small/medium cam in it. That will give you a lot of extra kick you will be pleased with while keeping the machine work at a minimum, and the revs low. This will yield good results while saving a lot of money.