You can pervert HC-110 to get a pretty good developer as follows, if you want something close to Ilfosol-S.
Add 50 grams of ascorbic or erythorbic acid to enough triethanolamine (TEA) to make 750 ml and heat enough to dissolve. Add 250 ml of HC110 concentrate. Dilute 1 + 50 for use with most films. It's good on HP5+.