Decision: 5x4 (SBP) or 5x4.5?

Howdy, I'm facing a decision on my 1969 Cuda rebuild.

Question #1: Should I go with 5x4 (SBP) or 5x4.5? What are the advantages and disadvantages or each? I already have these in photo. They appear to be original, 5x4 (SBP) and are 14 inches by 5.5 wide. Someone told me they are somewhat valuable and desirable. Should I keep them or move on to 5x4.5 so I have more options? I'm trying to stay original, does the bolt pattern really matter?

Question #2: I want to go with power disc brakes on the front, but can only locate the 5x4 (SBP) at PirateJack.com. Is that a good conversion kit? Anyone have insight into that conversion kit? Or again, should I go with 5x4.5 so I have more rim, tire and brake options?

Question #3: Should I convert to 4 wheel disc, or is it not necessary? Any advantages of 4 disc vs. 2 front in terms of maintenance, ease of install, etc.?
Apprecaiate all feedback, thanks.

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