Removing the crankshaft boss that drives the blade disc is a matter of technique, rather than equipment, as it's a taper fit. You just need two hammers, or one plus a solid 'anvil'. See this past thread for the details;
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=53044Also, check the cylinder bore for ovality. The 160cc Victas, with their short piston skirt, have a tendency to wear oval. That, rather than overall wear, tends to determine when a rebore is required.
1974 was the first year of roller small ends in the Victa 160's, so yours just missed out.
The small end bush is easy to replace, if you have the new bush on hand. Just use the new bush to press the old bush out. A suitable deep series socket makes a good support for the small end eye. This can even be done in a decent vise with soft jaws, if need be. Then any oil holes can be drilled, and/or the oil slot cut with a hacksaw - a fine 32tpi blade works best.
If you haven't acquired a spark plug tap yet, ISO M14x1.25 is the thread spec.
