mag heads. what retainers/locks should I use?

New EQ enginequest mag heads. will be raced only. new 8MM Hughes valves that are a bit longer than the OE valves that are on another OE mag head. the spring pockets are ~1&3/8 & I had heard that opening the seats up to use common 1.5" springs is a good plan & Goodsen has a cutter/pilot for ~$60. what retainer/locks should I get & should I stay with 7 deg or go to 10 deg. the OE retainers/locks do fit the EQ's but I did not mockup to see what installed height I have to work with & I have not finalized on springs either. the 2 cams I have are .571" and 535" lift. Thank you for your time.