I float between two stools while porting. I have a great rotator for porting heads that I and stop in any position. I like doing intakes but to get them blocked in the right spot I use the two stools, a piece of 4 x 4, a piece of 1.5 x 1.5 wood, a piece of 2 x 4, and two 1/2 inch thick pieces of plastic cutting board to square them up while standing end for end. Then of coarse my homemade V blocks. But you still end up standing a lot while porting intake manifolds.
