The 429SCJ heads are used in a variety of ways. Not all customers need a port this large. The valves are nice and big, but the big port ruins the torque.
These 8 aluminum inserts are pretty much to size, so when you install them there will be no need to mill off any material that might stick out of port.
Use 2 C-clamps, one at the front edge of port and one in the back. You know that the area in the back, (short side radius) is the most difficult to work on with a sanding roll. So, if you take your time installing the inserts and use 2 C-clamps per port, you should be able to tweek these out with a 3/8” sanding roll in very little time.
Directing the flow in the intake port is one of the better and more horse power producing ideas that has come along done the pike. Put it where you want it and enjoy the results.
This kit includes: the 8 inserts, glue and 8 button head bolts with instructions.