I'm not sure why you'd want to do this, but here's my opinion. Diesel combustion cycles are handled differently than gasoline combustion cycles. You'd have to make so many changes to the diesel head, not counting any machining to mate it to the gasoline engine, that it would be cost-prohibitive, IMHO.
If you decide to attempt this swap, please post your process with a detailed write-up and lots of photos. I'd be very interested in the results.
Would anyone know if you could fit a diesel head on a gas engine?
ONLY if they were the same engine family to begin with. That would leave you with an Olds diesel as the only one I could think of without research. There may be other farm equipment engines or maybe Mercedes Benz or BMW where the same basic engine was produced in gas and diesel.
I doubt you would find any such engine newer than 20-30 years.
In any event, you would not be able to just swap the head and have it run on diesel. Diesel requires much higher compression than the gas block would provide, depending on a number of things. And the cams are different. Plus, you need some kind of fuel injection system. And after all that, the gas motor internals are not up to the higher compression and cylinder pressures etc.
In short, you would be better to buy a diesel motor to start with.
anything can be done...bottom line. it all depends on how deep your pockets are, and how much time you can spare. i'd start by getting some dimensions between the two blocks. determine bore spacing, bolt hole sizes/locations, water jacket ports, etc. many have used cleveland and LS6 heads for inlines, volvo heads for the 2.3L, the list goes on. there's a lot of homework and legwork to be done to take on something like this. gotta decide how much its really worth it to you and what your realistic goals are for the build.