...more fun on this, a smart brain with a pair of sharp eyes noticed that the block on the car was a 302 block...So anything could be true, as I see;
- Yes, DeT really did have 3 engines--a 289, a 302, and a "302e" (Euro) are documented in the parts book. There are dozens of parts (solo 289) exceptions for the 289, including air filter, jackshaft casting, headers, the bell housing (w/o smog pump arm), etc.
- On Provamo, my count is ~22 cars claiming to have a 289--not just early cars (508, 512, 518, 528) but in fact all the way to the end (1200, 1212, 1292) and in between likely some mistakes (or example 8ma824 that lists their engine number as "502/059" and another car that looks like a US model (986).
One of the head scratchers has been availability of the 289, but (ignoring things like the engine numbers stamped on the Presidential motors) it seems that the 289 migrated to a 302 block in 1967 because of availability problems...Geez, the window dating on 886 (9 K) is even later than my window on 8ma1076--so lets assume that these Presidential DeT letters are invoices/orders, and the cars were built at least 6 months later...Meaning, important orders to deliver to customer ask but not especially urgent...
The claims of 305hp also started early (for example, the first reviews in ~spring 1969 in Auto Motor und Sport and shared in the French/German version of Sport Auto) both claim the 305hp is from cylinderhead changes and a Holley carb, that the ordinary 220hp version for the US was deliberate for better driveability in US traffic. Yeah, umm, this after 13,000 Hi-Po engines were put into Fords for the previous 6 years (with up to 11.6"1 compression ratio...!).
But though we probably equate 305HP with the Hi-po or the Shelby (with fabled valves at 1.84/1.54" as used on 351W...)--and this may be all wrong...Or at least, the DeT parts manual suggests that DeT themselves probably were building the "302E" and "289" engines--esp, listing the 600cfm Autolite 4100 carb and the Ford Hi-po camshaft. Yeah, strangely listing valve keepers for the 289/302e only, but quoting common pieces for all 3 engines (iron intake manifold, the valves themselves ordinary 1.78/1.45" as used on all 302...), and no callout for heads. Even, DeT only listed 2 part numbers for the whole engines (one for 289, one for the 302, so not distinguishing the 302e as a complete spare).
The Ford hi-po cam used was stout, a single-pattern,, high lift, long duration mechanical cam. The K-code engine used both stouter crankshaft journals and also screw-in studs for the adjustable mechanical lifter valve-train---but there is nothing in the DeT parts description for these pieces that I can find. Maybe DeT took their chances, if anybody has taken apart a Euro engine it would be fun to know. My guess, these look like an ordinary station wagon with 2v carb.
Btw, I was surprised a few weeks ago to see that in fact, all "manual trans" 302 engines in that time were shipped with the thermactor injectors--so another fun thing to understand were whether the 302e were built with engines intended for automatic applications, esp whether the thermactor ports were present/plugged and then the distributor would change (of course with the carb, but this was supposedly changed to 600cfm anyways...).
But for me who doubted the ubiquity of the 305hp quote for the euro cars--I think its reasonable that most the claims on having a 289 are wrong, but that DeT basically took the same route that Shelby took (headers+600fm carb with the K-code cam=305hp science that mathematically proves it 
).
