Yeah plugs will be an issue for sure, but until i get a donor engine to check clearances i dont even wanna think about it As is, i have to pull my dump pipe of my turbo to change plugs, but pulling the engine out every time i need a plug change will become a bit tedious...with a decent tune and a good set of iridium plugs tho...

Buy this

http://www.bennettracing.com/Crate%20En ... NGINE.html

Yeah i have always thougt about doing it to myXR but after looing at the 390FE block that i have and then the engine bay it was a case of yeah its Dooable BUT and this is where my major concern was, for one Chassis strength then the whle issue of haveing to re do the entire front end suspension set up and big brakes to pull her up. Also the whole having to muck around with the trans and new diffs etc etc not say it is s**t but very involving, if your keen do it would be f**k awesome.
Good Luck

i have seen a article about a American who sore mad max and brought a xb and put a Donovan on it i think it was a 750 or 650 or something shrug

the big block will also be heavy, so handling will suffer - if thats a concern.