Originally Posted by
megalowmatt
I'd say no. Looks like the frame is a little big for you.
This. If the saddle height is set for you then the frame is too big. If the frame does fit, I wouldn't replace the wheelset unless it has issues. Plenty of decent 27" tires out there to choose from. Replacing the cassette/freewheel to get better gearing could be OK as long as the existing RD can handle the larger cogs. You'll need to replace the chain as well as it will be short.