How to Clay a Piston
Clay'n the piston to verify piston to valve clearances. It isn't all that difficult.
Apply a small amount of modeling clay or play doe (the old school type) to the pistons valve pockets. Assemble the top end completely, using the old compressed head gasket, leaving out the spark plug (for no compression). Adjust valve lash to spec. Personally, I don't install the rings on the piston ether. Its makes clean up of clay Little easer if clay is over applied. I also use a LITTLE Pam cooking spray on the head/valve and base gasket to prevent sticking to the modeling clay and cylinder.
Rotate engine over by hand slowly. You will experience resistants when the cam comes upon the valve spring presser, and when valves pushes against the clay. Continue past it. If there is a sudden stop in movement! Dissemble and Inspect the valve imprint in the clay. If you see contact with the piston you with need to ether clearance the piston or sink the valves. To measure the depth of the clay use the tale end of vernier caliper, depth gauge to penetrate through the clay to the piston. Or any other tequnice that will be accurate.
Cam manufactures recommend some were around .060" on the exhaust side. Check with manufactures for clearance recommendations.
I personal haven't heard of any one reporting issues with the TB 132 kit and aftermarket cams. Beside Socal thoughts in the big bore thread. And Firepower354's valve collusion issues at overlap. There are a few TT members ruining after market cams with less lift (Hot cams and Takegawa stage 1) in the 132 kit with no problems.
Hope this helps