taper on lift block?

[bladerogers]

Hello. Im sorry if this has already been asked but i couldn't seem to find this question on the site. My friend and i at work both have k20s and he has a 4" lift. his blocks were made for him by a machine shop friend of ours. however he would like the guy to put a taper on the blocks for his drive shaft angle. has anybody done this themselves? if so how many degrees? or any other tips?