i would return that head, the previous owner to my 87 d50 put a non jet valve head on it and it runs like crap. they lowered the compression from 9.2 to 8.8 and that along with the removal of the third valve and that crappy carb will make it run horrible. I even stuck my 38 38 on the 87 (restoring engine out 82 to put in 87) and it did almost nothing.

the jet valve actually helped with performance while reducing emissions. that's why a 87 is so much faster than a 82, even with its increased weight.