Cold set frame or spacers?

I know I'm dragging up an old thread here but I've used the search and this seems the best one.

I have 2 frames where I want to increase the rear dropout spacing. Both are steel.

1st one is a very old (40's/50's) track frame I want to respace from 110 to 120.

Goodhead -- did you get anywhere with respacing the old track frame for 120mm?

I have same issue with 1950s frame - I guess it affects the chainline somehow?

by the way I found that older 126 road ends can easily be sprung for new 130mm hubs - giving 20 speeds with downtube shifters.