I believe the "Rev-Kit", is an early ProStock Engr. design (adaption) for an FE; reinforced by the use of PSE rocker shaft end stands, retained by the "longer" cylinder head studs.

I ordered a '67 R-code Fairlane 2dr in late Dec. '66 that wasn't built until mid-May '67 and, even then, it was fitted with a manifold requiring the larger diameter thermostat.

X2 on Ohio Crankshaft, 5453 SR49 (S), Greenville, OH 45231, 800-333-7113. Not very near to Columbus; due West of Columbus near the IN/OH state line, North of Dayton. They do fantastic work on crankshafts. Good luck.

Great folks to deal with. A few years back we made the decision to restore our original, '67 R-code Fairlane Coupe to "day one". When the car was delivered it was adapted into an NHRA Stock/SuperStock competitor which meant converting to drum brakes/removing all the disc brake-specific parts including the brake booster with 32 actual miles showing on the odometer. With a limited resale market the decision was made to simply store it on a shelf in the shop. Fast forward to 2005, before re-installing all the disc brake parts the booster was sent to Booster Dewey for rebuild. Booster Dewey returned the original booster with a note saying that they had carefully inspected the booster and found it needed "nothing". They were so careful that I couldn't find any evidence that it had been opened and it still retained it's factory grease pencil marks from the OEM assembly line. The most unbelievable part of the story was they did not charge for the inspection also thanking me for permitting them to witness such a historical part in pristine condition. Every once in a while you are surprised when someone does something out of the ordinary.

I you have access to a "spare" trans slip yoke you could remove the drive shaft: you will, mostly, be doing that anyway when installing the new diff., install bare slip yoke in trans and re-run test as before. That will isolate or eliminate the trans as possible contributor. Good luck.

The alcohol content in today's street fuels is said to drastically shorten the life of neoprene lines without the teflon liner. My experience purchasing fuel lines has been that the teflon lined types are normally less than a twenty percent up charge over the plain, unlined, neoprene. Buy from a reputable source and avoid china imports.

There are a few different ways to restrict the oil to the valve train. One of those is restricting the oil coming to the rockers in the passage within the heads which terminates under a specific rocker stand on each engine bank. If reusing the head gaskets is a concern, then you may want to consider preparing the heads for the restrictors prior to install, that way you eliminate removing the heads for further work since it would then only necessitate removal of the rocker shaft assemblies to install the restrictors.