as above mentioned, I have used the arp nut/stud kit with a grp a for the 205 block and never had any problems other than they need to be retorqued now and then, and especially after the first few heat cycles. I've used standard head bolts on a t34.63 running a grp a gasket, peaking at 34psi holding 28 psi it lasted 3 years before the engine dropped 4 valves onto its pistons.

As you have said though the final finishing faces of both block and head need to be very fine for a mlr gasket, and they can be more susceptible to oil leaks than a group A,
Also if you still have an early 3dr head Id have a look at getting the water jackets on the exhaust side welded and drilled , to reduce the chance of gasket failure.