Hi, I assume that this is in an L20b? I have a few ideas concerning your problems.

Sounds like the exhaust lobes are ground to "471c" profile and intakes to "477c" (whatever that means to Wade). Nothing wrong with this, it gives your intake the fast opening (and obviously higher lift) needed to get good initial flow, good for torque throughout the rev range.

I think stock L20b duration at 50thou lift was about 204 degrees, with about 410 thou total valve lift, so your exhaust profile is basically stock with a little more lift, and your intake being 212 would be termed a 'sports' profile, but with extra high lift. Overall I think it would be an excellent street turbo cam (mild), clearances of 12thou is normal and safe, usually you go 2 thou less on the intake but considering the intake profile is rather aggressive in its opening I think their figures are fine. Stock is 8(I) and 10(E) thou cold, I think. If in fact the cam does lift the intake valve that high (specs often vary from the real world) you would basically be binding the inlet springs, the datsun books reckon they bind just over 460thou lift (I've never lifted stock springs that far) - you'd better check that VERY SOON or you'll wipe out your inlet lobes or drop the rockers. Maybe crank it by hand with a 10thou feeler guage between the spring coils to see if it binds on the guage.

***This cam will certainly create more OVERLAP than a stock one (unless the lobe centres are over about 112-114 degrees, you can calculate that from the opening and closing figures), your main problem with an EFI system is upsetting the MAP signal at idle and low speed due to this overlap and the later closing inlet valve. What inlet manifold vacuum does it pull at idle? Any increased overlap creates LESS vacuum in the inlet at idle and low speed, the ECU sees this as more throttle and will select a higher load zone. Do you have a Throttle Position Sensor? If you have a TPS installed you must select it to control the load selection at idle, or until the engine makes boost (ecus differ on how they use the tps signal). This enables correct selection of the load zones in the ecu. You may also find you can advance the ignition timing at idle/low speed with the cam because the low vacuum caused by the overlap actually means there is lower cylinder pressure and additional advance helps smooth things out (I run 38 degrees advance at idle with my L20B turbo and "wildish" cam - more duration than you but moderate lift). Cam selection goes hand in hand with turbo size, you should get very good streetable performance with that cam if your turbo is around the T28 -T3 size, should be very responsive and driveable.

ALL THAT BEING SAID - if you're out a tooth on the chain when you installed it, it'll run like crap regardless.