The intake cams are interchangable between the GE and GTE motors and any aftermarket one will work. As for the exhaust side the only reputable cams I've found are from Eric at TTC Performance over in WinterHaven. If you send him your Exhaust cam he can have it hardwelded and reground to any duration you want. I had him do mine in a 268, you can go alot higher depending on what turbo your running and weather or not your going to run shimless buckets. If you want a nice idle though I'd stay under 272 unless your idling at like 1100rpm.