I am making an assumption that a 2.5 lightly modified Duratec, with around 220bhp and 200ft/lbs would be considerably less than a Cosworth? But if the prices are the same, then, yes buy a Cosworth crate engine.
Frankly, I just like the idea of getting rid of the leaf springs, if nothing else, air suspension could also be fitted if kitchen stoves were to be carried on the rack, or on 4 seaters.
Probably a kg or so heavier, due to the taller block.
As a matter of interest, I bought a 7000 mile 200bhp 2.3 Cosworth from a written off Caterham for £6,000 a year or two back, but it did come with exhaust, ECU, engine mounts, prop shaft dry sump, alternator etc ready to drop in, all that stuff may have to be added to a crate engine, so beware, the price on the sticker may not be the total cost of installation!
Good deal, Paul. So 1 Kg is almost less than a lunch (or two). Is a Cosworth heavier than a standard engine due to added throttle bodies etc? If so how much would you estimate?