Ok so you spoke to IDM how did that go??
I built my stroker 400 with them. The IDM bill was under $1800 and the 440 Source bill was around $3600 with Stealth heads.
IDM: had to Clean/Sonic/Mag/Bore(with plates)/Line Hone/Deck Block, chase all holes etc... Since I don't buzz this motor I used stock caps but all new ARP hardware. They magnifluxed all the new parts, measured all the new parts and assembled them. We did the same with the new heads and changed the springs and retainers. They degreed the cam and got the compression to 10.5.
I had tins cleaned there and they assembled the longblock due to my injuries. They were and are good guys. I stop in all the time doing one thing or another there. Hope this helps.
Ron