Doesn't the 86 have flattop pistons that have minimal valve reliefs, and don't match up to most Cylinder Heads? - Maybe the GT40's will clear the pistons. Just want to clarify....
Your camshaft and rocker arm ratio will determine PTV clearance for the most part, not the cylinder head. As with any HCI setup, you will need to clay the pistons. Some clear flat tops/GT40 on the stock cam, some don't. If they don't, the valve relief tool is cheap and easy to use (your machine shop should have one as well). The overall point was that you are far better off just honing the bottom end and assembling with the stock cam and new bearings and putting that $$$ into a craigslist set of heads and intake manifold then worrying about machine work to the bottom end and a cam. If there isn't a scratch in a cylinder wall that catches your fingernail ask them to light hone and hot tank everything, reassemble.