New here - 1991 GT Team Avalanche

[shogun]

Change the freehub body to an 8 speed one (buy a cheap 8/9 speed hub on ebay) , fiddle the axle spacers, redish wheel slightly and bolt an 8 speed cassette on.

Is there any advantage to doing it this way? Just seems to be additional cost and work over the 8 of 9 option, will one or other index better with the alternative cable routing or can I get away with out that for an 8spd cassette as the spacing is closer so kind off within tolerances?

It's still pretty cheap, bolt on any 8 speed cassette and away you go or slip a spacer on and back to 7 speed no worries. Also you get a new freehub into the bargain at the end of the day. Apart from a cheap donor hub it's all simple fiddling to make it go.

But if you can make it index, well either way works.