Your idea seems iffy to me. I think you run a real risk of the epoxy "plug" (or pieces of it) falling out and getting sucked into your intake valve (or combustion chamber).
The area you want to fill is rather smooth, and kind of "cone" shaped with the large end of the cone pointing into the runner...in other words, there'* really nothing i see that will securely hold that cured epoxy "plug" in place. Also, with thermal expansion of the cast iron, I foresee the epoxy plug actively wedging itself out.
If you must do this, you might consider high-temp RTV...it is less likely to wedge or "pop" out, and far less likely to destroy a valve or piston if it does fall out.
Best of all would be to find a set of those 8134 heads without the injector pockets and use them for project heads...
2004 Buick Lesabre Limited, Gran Touring; Bone Stock
1998 Buick Lesabre Limited, Gran Touring; Mods: Poly sway bushings/endlinks, Tru-Cool trans cooler, Thrasher shift kit (med), PLIM, front PEM; Mods in progress: Alot of stuff, but slowly...