valve piston clearance

You will most likely have problams. TFS heads rotated the valves to match the factory notches. All others are inline and will need clearance checked.

Actually the TFS heads have rotated valves and due to that design they allow the 2.20 intake valve. The factory pistons are made for a inline valve head.

Most 2.02 inline valve heads will fit, however you need a near stock cam duration and cam timing.. They usually hit on the very outside edge of the eyebrow, if you ever float the valves it will hit. You really do not need any more depth you need radial clearance, you can buy the Isky tool and notch the pistons yourself.

EVERY motor is diffferent......
 
A TFS TW head is an in-line head.

With no side cant, as long as the stems are together, they are in-line. Just the TFS TW has a rotated chamber.
Quote from Jay Allen (Camshaft Innovations)

All of the heads you guys talked about are inline. The valve stems at each cylinder are inline with one another.
A big block Chevy would have non-inline valves or canted.