D3s are the same as D0VE-C heads except for the D3s have larger chambers. Compression with a flat top piston won't be anywhere near 10:1 if that's what you're looking for but other than the chamber, the heads are the same. Good heads to use with the dome TRW pistons though.
The D3 heads have good flame travel and a good closed chamber design. It's the D2 heads which have an open chamber and should be thrown away under all circumstances but the D3 is a revised D0VE casting with larger chambers using the closed chamber design. Excellent heads to use for lower compression.