use citrusstrip gel to remove the varnish. easy as pie. available at yer local big box hardware store.
I can send you a bamboo scrap for test wrapping- a spool of silk in a funky color too.
I highly recommend varnishing test wraps to see what you want.
refinishing a bamboo rod is a very rewarding experience. by all means replace the guides, add a few more and make the rod a better fishing tool. you can make that thing look brand new.