It really depends on what model you have, but here are the basics (trust me i know...i am on my 5th del sol)
S models share the same engine/trans/axles/brakes/suspension parts with the 92-95 civic dx (the shocks and springs will fit but they are not as stiff as del sol's)
Si models share the same engine with the civic EX, but they have rear disc brakes, which are the same as what is on any 94-01 integra, or 92-95 civic si.
VTEC models have a suspension almost identical to the integra (the only difference being a 1 mm larger rear sway bar, and the emergency brake cables arent the right length.
As far as the body panels and interior parts go, they are all unique to the del sol, and can be a little harder to find.
If you are going from a D to a B series, you will just need to use the integra motor mounts. You will need to locate a del sol VTEC shift linkage, or modify an integra linkage. I dont recommend modifying the linkage unless you know what your doing though. The linkage that I modified turned out like a stock del sol VTEC linkage, but it took me 3 or 4 hours and I had to cut and weld a couple of times.
The exhaust is fairly similar to an integra or civic, but some minor modification needs to be done in order to get it to fit (cut and rewelded in one or 2 places)