Get the stripped blocks taped and Helicoiled, And in future leave a .5mm gap between the body and block and use a little PTFE tape on the pump arm to take up the slack on the threads.
I think you'll need 1/4 UNF Helicoile and the appropriate size tap.
Belsales should be able to do it for you or there’s one or two engineering tech heads on here capable if you ask nicely.