They'll work fine. Since it's 4x5 and unless you're making huge prints, grain will never be an issue from Delta 100. You'll get a bit more film speed and less grain from Xtol, but do you care? D76 has a slightly different curve which some prefer to what Xtol does, and vice-versa. You might get slightly cleaner scans from Xtol - I do on some coarser films - but I haven't verified that with Delta 100.
Personally I do everything in Xtol (I can wring every last drop of speed/grain from TMY2 with it, and why keep two developers?), but I think D76 is a perfectly good choice here.