512 stroker.

The lower end parts are good value. However they need to be carefully inspected and measured. IMO, unless you have the proper micrometers and have done it, have a trusted shop do this. The rods need to be cycled with the correct thread lube (because they are not finish machined iwth it). I have had 5 kits over a few years, various rods including the 505/512 kit's 7.100 rod, and I have yet to have a set of rods pass muster. They will also need the pin ends honed. You sould also have the assembly balanced by your shop, not Source.
The heads are also decent, but as the rods, have a couple weak points: You need to repalce the springs, retainers, and locks and the valve job needs to be checked. The valve job operations also need to be done with Edelbrock and Indy products so not a huge deal. The Stealths are a very close copy of RPMs, and on a 512" engine will run very well out of the box. But, they are smallish for that stroke.