I was lucky enough to get 100% of the parts needed for a R5 P7 build From Scott E. but ive wanted to let things go a few years and see how some builds went to decide on mine.
Now the hard part is finding a machine shop within 200 miles of me that can handle the work.
Although I hate to say the open space? block looks like a LS1 in style alone so there should be someplace to do it.
My local napa is good for older blocks and inline 6 tractor blocks as well.
From the static vs dynamic topic I think im in trouble on my current R block build at 13.9:1