I've searched for years for an alternative to the plastic blocks because they are fragile and I couldn't hang a starter from the SBC one I had. I used a P-Ayr plastic LS block for designing motor mounts. I wouldn't do it again. When compared to the parts I had laser cut off GM 3D computer drawing files I use I found the plastic blocks had way too much variance. I didn't have the problem with the SBC block from P-Ayr. I would highly suggest finding an aluminum block LS and gutting it. Once I did this everything fit properly with exceptionally good tolerance. I centered a Harbor Freight electric hoist directly over where I did test fitting of powertrains and this made it easy without the stupid cherry picker legs getting stuck under the frame.
