Chris is right, the piston/crank relationship is a primary interference point, so be sure you get a known combo for the fewest issues. Scat is generally pretty good about that area. Actually, there are several checkpoints and some do depend on what rod you use. Some rods are very fat on the big end and will require checking for interference on both the block (pan rail & cylinder bottom areas) and the camshaft. Mock-ups are the word of the day.
To make life easier, you may want to take a rod to the hardware store and look for a stock-sized spring that will fit the piston pin bore and be just over 4" overall. This replaces the piston during some mock-ups and keeps the rod centered in the bore, while allowing more room and visual angles to clearance checking. Oh, and put some chair leg caps on the ends of the springs so they don't rub the bore metal-to-metal. If block clearance is required, it won't be much, and a light hit with a Dremel or die grinder will give the clearance you need. Have fun!
David
Piston/crank clearance - block upside-down on stand. Also note the semi-circle notch on the right side of the cylinder bore for the
other rod to clear:
