There is an easy way to modify your existing timing plate to make it work without changing it out. It can be done without removing the timing plate or the camshaft. You do have to remove the harmonic balancer.
In a nutshell, you drill two holes in the bottom of your existing timing plate and weld in two nuts so that you can run a bolt from the bottom up instead of using the carriage bolts from the top down. As I recall, the carriage bolts are 7/16" fine threads, so that's the nut/bolt combination that I used.
You can get the measurements for the holes at Deve's website. Here is a link. Drop down to 'Modification of the Timing Plate".
http://devestechnet.com/Home/Project1959235I used his measurement to mark the holes when I did it. After I drilled the holes, I held the nuts in place by tightening them with the new bolts while I welded them in place.
Easier to do than changing out the timing plate. And you don't have to mess with the carriage bolts in the future.
Matt