318 Difference?

I'd be turning the crank anyway so if the 70 crank is not that bad, I would just have it turned and use the next undersize bearings.

I never have 'just honed' the cylinders since I was a poor college student rebuilding an old F300 292 ci. It too often ends up being a waste of time and you don't get good performance, often have a lot of blow by, and the engine doesn't last that long. So JIMO, no, plan on boring it and put in new pistons. You can do the measurements to check for taper and out-of-roundness to see how good or bad they bores are, but I bet they are all tapered to a degree; that'll wear the rings fast. If you do just hone, make sure the ring ridge is all reamed out or you'll break your nice new top rings.