the reason i asked what engine you are planning was to do with you saying you have tacked the TR5 into place, i,m using the 1.8cvh engine & had to cut the TR5 tube out as it fouls the carb/manifold, not sure if it causes a prob with other engines, but as the book was written using a pinto engine then i presume it,ll be fine if you do get the pinto,d sierra,
i would think hard about changing from car engine to bike engine after IVA, lots of things to change, maybe go bike engine from the beginning??? speak to Slimtater & Tilly as they have bike engines in their Roadsters, Slims is already been SVA,d & Tilly,s is a current build, maybe they could give you some advice on bike engined Roadsters.
cheers
andy