for the cost of the new studs I would replace. When will you next have the manifold off in another 9 years time by which point the studs will be 18 years old. Bolts will work fine but studs are always best.
When I re-built my 1981 Xflow over the winter I put in all new bolts as I reckoned it may be another 30 years before it is taken apart again!
Would love to cme and help, engine work is so rewarding.
