Heres the cool thing about the Alterktion ( one of the reasons i bought it), a center sump or rear sump oil pan will clear, as well as headers. Also, i believe the oil filter can stay on the block with no need to make it remote (off the block). If ya already have a remote filter, all you need is the center sump (with the stock k-frame). Not sure why they are having fitting issues with your mounts. I had Bill at RMS make hemi mounts for my Alterktion and they fit well (took me a little while to figure them out). If you already have most the stuff for the stock suspension, id say just go with it for now. getting to drive you car is the most important thing in my opinion. As you said, later you can just get the alterktion if you feel like ya need it. I think its an awsome system, but it can wait till youve gotten to drive your car for awhile. If later you want the alterktion, you can still use your center sump and remote filter (although i think having the filter on the block looks nicer). As far as the mounts, im guessing youll have to have Bill make you some hemi mounts for your alterktion.
Are you gonna use headers? if so they might be real tight with the stock K frame and gear box. You might want to wait for headers till ya deside if ya want an alterktion.
Hope this helps
