The engine serial number is on a boss on the passenger side near the motor mount. That will tell the story on the year of the engine. The main differences between the FI engine and the Carbed engine is there will be no provision of a mechanical fuel pump...the boss is there and even the bolt holes are there, but the boss is not milled and the hole for the pump is not machined out...and the later model engine may (or may not) have 1/2" head bolts, while the early engine has 7/16" head bolts...the heads are not directly interchangable. The 1/2" size headbolts size is desireable because of the increased clamping force. It *may* be possible to drill the early head for the larger bolts..don't know for sure, but Bennie @ Hesco can answer that.Other than that, the timing cover is most likely different because the accessory mount brackets are different.
Boring the engine to max over will offer little in performance...Port the head (unlike the 4.0 H.O vs. Renix there is no difference in the intake ports), install a set of Mopar S/S valves and associated hardware, and a good cam..(with a manual tranny the Hesco RVOB cam is a good choice. If you are staying with the carb instead of going to EFI, a Weber 38DGES is a good choice. If you go that route, get an intake from a MPI engine and modify it to mount the carb, it will allow more room for a proper air filter, and the runner/plenum volume will help build more torque. Resist the urge to buy the Clifford intake...their headers do fit well though...as an alternative you can use the stock exhaust manifold from a MPI engine (nearly as free flowing as a header and more durable.
As for the SYE...I haven't needed one on my 85 model with a 207...I did clearance the yokes to prevent bind at full droop. With proper axle shim and a mount drop kit, no vibes at all.
