The injectors were stock 6.5 injectors, new with the rebuild though. IIRC, the cam was around $150 or so. If you like I can get you their number. the only problem I've had with the heads or valve train is the little plastic "buttons" that retain the rocker arms. There are upgraded units out there, I've seen them on ebay before. If the engine in your '94 is origional it is considered one of the best out there. The '599 casting number blocks were used from late '91 through '94. The current best is considered AMG Hummer's new "enhanced" block that has thicker mains and a higher nickled content in the block. These can be identified by a Navistar casting logo in the valley of the block. The only ones to stay away from are the late '96 to '00 blocks that have the '506 casting number. The other good blocks are the first 6.2's from late '81-'82. They had high nickle content, but the only identifying characteristic is they were the only ones painted red from the factory. The only place I know that sells girdle kits for these is a place called DSG out of Canada. The splayed mains can be had from Kennedy diesel in WI, but I've heard a lot of negatives about his service. ARP makes stud kit for these motors, main studs, head studs, and I think even upgraded rod studs. I would most likely leave the heads alone, maybe polish them up, but leave it at that. They are prone to cracking somewhat, I wouldn't want to increase that risk. The main restriction in the system is the precups in the head anyways. I've thought about porting the holes in them out, but never done it yet. I've also thought about o-ringing the head, but once again haven't got to it yet. Origionally I ran a few different Garret turbo's, but wasn't satisfied with performance, so I got a WH1C Holset. It was awsome, good spoolup, lots of boost, but it died to turbo bark... The current one is a Hy-35. Spoolup is instant, boost is also good, and with the fueling level of the 6.5 EGT's aren't and issue like they are on the Cummins.
Justin