Hey Cris, just tell the shop what you want, the most power you can get safely and reliable. If they are Detroit 2 stroke guys they should have a solution for you.
The difference between the injectors is one allows you to put more fuel into the engine if you choose. The 65 will take that choice away.
Their engine had 70's it's well documented by the 2 they had no smoke I setting up a 8v71 NA now with the 70's it had no prior smoke either just don't use A timing