These two engines are wider, but not significantly longer, than the engines that originally came in the E30. We both know the V12 is essentially a pair of M20s siamesed into one block - so it's about a half a cylinder longer than an eta. It's only wider on the left, where BMW had gotten into the habit of throwing stuff like brake boosters and power steering pumps. Those things can get relocated just as they did when the V12 went into the E38 in place of the M30. I would guess (not knowing for sure, but open to correction) that the V10 is even shorter than the M20. Since you're asking ... no. It's only that, like the '55 Chevy, BMW made a (relative) boatload of 'em and they're cheap to buy. It's clear from your last message that you're intrigued by the idea of a Ford V8 in an E38. I would not begrudge you doing that. I think it'd be a great idea.