Spada camchain tensioner repair

Hey trendsetters,

It's been a while since I last posted to this forum- my bike has been
running great. Howver it's definitely time to do the camchains at
65,000km.
The tensioner on the rearward cylinder is shot- definitely the cause
of my rattly top-end noises on warm-up i reckon.
I was just wondering if there is any way to get the
tensioners/camchchains out without removing both camshafts.
My other question is: in removing the camshafts you remove over half
of the cylinder head bolts. is there any problem with me just
replacing and torquing these bolts after i'm finished, or should i
replace the head gasket???

Hellip!

Chris