I am pondering on replacing 6X-4 heads as a winter project and would like to get feedback of cost vs performance. My 6X heads were rebuilt with stainless valves and milled slightly to square things up. The 400 cam is roughly 226 @ 50 with 465 lift (1.6 roller rockers) should be around 490 lift. The bottom end is 2 bolt main , forged flat top pistons ect. Preformer manifold , MDS ignition, underdrive pullys, windage tray, crank scraper, quadrajet carb, supercomp headers, 350 Turbo (3000 stall) 3:42 posi disc. I had the short block built by a local shop Kammer / Kammer and it seemed like forever to get those rings seated (molly). This project would cost roughly 3K plus time and I am not sure if it is worth the $$.