I'm reviving a friend's beloved 1980s-vintage Trek 420 (she rode it across Europe in her 20s) on a tight budget. I replaced her worn out 126mm Helicomatic hub/freewheel with a cheap 130mm threaded Dimension replacement wheel and installed a Shimano Tourney (MF TZ20) freewheel. It's a snug fit in the dropouts, but I didn't have to bend anything.

Here's the problem: When I went to adjust the shifting on her Simplex derailleur, I could get the out limit to line up, but the inner limit stops just shy of allowing the chain to shift onto the lowest gear. Close, but no cigar.

So I'm wondering if I could fix this by playing around with spacers on the axle, just to move the cluster a couple millimeters toward the drive side. The option is I just eat the cost of this wheel and spend more to replace it with a 126mm 630 ISO wheel.

Thoughts?