Since it is going to be temporary, I believe it would be easiest to convert it to carb. This assumes your Pinto came with the carb, manifolds, etc. On the 88 long block replace the oil pan and pump pick up with the Pinto's front sump parts. The dip stick needs to be moved to the front. The 88 will have a boss for the front dip stick but you may have to drill it out. The hole for the mechanical fuel pump should be in the block, just remove the cover and install the Pinto pump. You may need the aux shaft from the Pinto for the eccentric to drive the fuel pump (not certain on this). Then swap the long blocks out using the Pinto manifolds, carb, motor mounts, etc. There will be a intake port mismatch, but I suspect it will still work temporarily (may have some puddling). Depending on what front accessories you want, using the 88 serpentine belt or using the Pinto V belts will be up to you. Have fun.
If the intake port mismatch becomes a problem, the companies below sell adapter plates to use the EFI lower manifold with a carb. Check hood clearance.
www.esslingera cing.comwww.racerwalsh .comwww.raceeng.co m