Gear ratios and hills - halp
So, I'm new to this road cycling business, having come from MTB, and I'm having a bit of a headache with gear ratios. The bike I've picked up has early 90's Chorus and Mirage kit, 8-speed, and is currently set up with 53/42 on the front, 175mm cranks, and a gnarly 11-21 cassette. I'm reasonably fit but I'm carrying a fair amount of weight for 6ft, and that 42-21 gear isn't cutting it for many of the hills and hillocks around here.
I've just ordered a new 39t chainring and a 13-26 cassette to rectify this, but I'm now having second thoughts about the back. Should I stick to a 12-23 instead? I don't especially want to lose the 12t, especially with such long cranks, and it's hardly mountainous in Norfolk, but I'm used to being able to spin up any hill on a MTB triple and grinding up even small hills is knackering me. Any thoughts?
TL:DR, sacrifice climbing versatility or top speed for new-ish road rider?