+ for IAR-80/81.
The Romanians did made a test model with a Jumo 211 engine (because they had them for the SM-79). Away from the literature, from memory I think they had issues with fuselage/tail vibration and the general conclusion was that the airframe was a little too small for the weight/power of the Jumo (it was a follow up of the PZL 7/11 fighters series from early 30' after all).
Recent literature actually says that both the DB-601 and 605 were tried on the IAR-80. First in 1941 IAR-80 no.13 had a DB-601 from a Bf-109E, indeed it vibrated badly. Second time in 1943 IAR-81C no.326 had a DB-605A fitted, this time it flew quite well (probably because the 81C airframe was stronger since it was planned as a dive-bomber), but the germans didn't give us any engines for production/conversion. I probably said it elsewhere, but i'd sell my soul to the devil to see pictures of this DB-605 powered IAR-80 (or indeed better ones of the DB-601/Jumo-211 airframe), must have been quite a sight.
There is a bit of unclarity re. Jumo-211 since recent literature does not mention such trials, BUT some speculate it might have been trialled as well, maybe in 1942. At any rate, apparently the IAR-80 was designed to have a Jumo-211 from early on, as far back as 1937 (same goes for the SM-79B order, which eventually evolved into the JRS-79B)! Estimated speed with a Jumo-211Da was 30 kph highter than the basic radial version, and at a higher altitude. But again, the germans did't give us the necessary engines, so the planned Jumo-211 powered IAR-80 production (from no. 21 onwards) never happened.
To top this all up, there is mention of an airframe with a 1600HP Gnome Rhone engine, which logically it can only be the Gnome Rhone-14R. But this never got to fly since it was destroyed in the USAAF factory bombing in i believe May 1944.
So yeah, this is the list of alternate IAR-80 variants (and i guess the wet drems of any 80 afficionados), with DB-601, 605, Jumo-211 and GR-14R. Any of these engines would have given the IAR-80 a new life.