If ran mildly, the 24 pounders would work fine with some boost in FP. If you have 36's though, just keep them, non sense in really getting rid of them. What determines the final injector size is your future plan with the engine: turbo/supercharger/nitrous? If staying n/a then just keep the 36's, they are a little on the over-the-top side but you can turn down the FP if need be and they give you some head room with the 347.