Souljim

Hi all, I’m taking down an old conservatory and extending it out to create a larger single storey extension. I’ve got some 25mm x 600mm steel bar to tie the new footings into the existing foundations and had a few questions. What size drill bit do I need? Is 26mm okay or do I need it to be slightly bigger (say 28mm) for the epoxy resin. I don’t want to buy an expensive resin gun to use it once either and I know you can buy some epoxy resins in a syringe that pre-mixes it. Any idea on which one’s best? Thanks