Seems the V8 guys have been doing this conversion successfully..... since our motors take the retrofit hyd roller lifters for a SBC.... I don't see why we couldn't use factory hydraulic roller tappets. Seems the V8 and 90 deg V6 lifters are too tall.... and are not very good candidates for the conversion..... because the higher lift cams might push the lifter up enough in the bore to block off the oil port....... or the "dogbone" will come up off the top of the lifter bore. It appears to me the 60 deg V6 lifter would work fine. You could use the lifters and dogbones from a 60 deg V6 and the spider from either factory hydraulic roller 3.8's, 4.3's, or any of the V8's that come with the spider.... you would just have to cut it down to fit. Here is some info I have found for the lifters: