Wow! Incredible effort.
I would try some Biofreeze or BenGay. I would also take 1/2 teaspoon of baking soda in a glass of water. The theory is it helps neutralize the lactic acid which has built up and is causing the soreness. It does this by creating a pH imbalance which draws the acid out of the cells.

I don't know your wheel size, but 42/20 with a 28c tire on a 700c rim is about 52 gear inches.

I ride a 44/17&18 on 32's which is roughly 70gi & 66gi. Again, great effort though. Hope the soreness leaves soon.