G'Day Tilly
Far easier to remove the rear rocker box studs, lower the box on from the inlet side, down past the springs and push it forward to clear the exhaust springs. If it still fouls the front studs may have to come out. Fit the pushrods, settle the box and then use your gynaecologist skills to re-insert the studs. Some ruffians use Whitworth hex head cap bolts, or even cut a screwdriver slot in the stud. I have seen boxes with indents cut to clear the springs, but this narrows the seal area for the rocker cover gasket.
I would be inclined to leave the head alone, get some miles in, see if it leaks. If you gave it a good bit of tighten, sleep easy.
Well done for getting it back together.
Swarfy.