High Back Seat mounting (low back conversion)

Replacing the seats in the '72 "special", the original front buckets were replaced with racing seats, I did get hold of a pair of high backs (which I have had re-trimmed to the B2 spec).  The seats did not come with mounting brackets (runners).  In my collection of parts I found a few pairs that I assume are all from Low Backs.  They do not line up with the '72 mounting holes.  It appears that I will have to modify some low back ones to fit the floor, then re-configure the rails to accept down pointing bolts instead of up pointing ones.  Anyone ever done the conversion?  Or is there tracks from an Escort/Cortina etc that will work.