Depending on the date code of your enigne it could be a good candidate for a GT-E Cougar. It sounds like you may only want to ue the block and some of the factory 427 blocks wre pretty thin on the cylinders. The heads would not be a much use to anyone but a restoration guy. You could advertise it on one of the Cougar sites.
There is really no need to go with a shorter stroke than the 4.250 unless you want to give up free power. We pretty much keep any conbination you would want or can get it real quick. The EFI is an option but remember that it is a little harder and more expensive after you get the engine and install in the car. You have to get special EFI pump, filters, return line, O2 sensors along with mounting the computer and running all of the wiring. I have on one of the engine that I did for mmy wifes car. The right stuff tuned right works great. There are units you could run on that side winder intake that is a throttle body with the injectors built into it. You would not have to drill on the intake or anything. If you go direct port injection you would not want use a dual plane but a single plane intake.
I even have a all aluminum 482C.I setting on the floor at has very conservative camshaft and runs on premium pump gas. It made about 585HP and over 600 ft/lbs of torque. 4340 steel crank with hydraulic roller carburetor to Moroso
oil pan of the dyno. This enigne can be had for 16,900.00 which is about 1000.00 less than out normal price for the same enigne.
Thanks, Keith Craft