Yes, the smartest way to build up this bargain is to keep it a bargain by using parts transferred from another old bike. Mtb components will work fine with a few possible issues, but the biggest one will be brake reach if you change form 27" to 700c (4mm smaller) and 26" mtb wheels will not be usable.
Others include:
1- your frame's rear axle width is probably 120 or 126mm, and the new wheel is probably wider, 130 or 135mm. It's no issue since you can spread the frame easily enough.
2- the front derailleur clamp diameter might be different
3- if you have a braze on mount FD, the fitting might be too high for an outer chainring 48t or smaller.
4- there might be chainstay clearance problems for the triple, solvable with a new BB or spindle.
5- there's a good chance the seat post is of a different diameter.
Other than that there might be other minor and surmountable issues and you can cross those bridges when you get to them.
__________________
FB
Chain-L site
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