170 length is the EASIEST to find in older components, not that mid 80's is that old. The biggest issue you will find with that Victory crankset is new chainrings, as it uses an obsolete 116mm BCD. But if you would like to replace that crankarm, try posting a WTB in the C&V forum. I don't have one, but someone there might.

IIRC, that crankset used a 115mm Campy taper spindle, which was also used on just about all Campy cranks post '77 up until the introduction of C-Record and the Chorus group, so you could could go slightly mis-matched as well.