Since you've started to work on them, might as well finish them and try them both ways! There's no no-no's here.
I've found that a lot of those preamp pedals are really mimicking the overdrive channels, and don't have as much clean on tap as you'd expect from the amps they are based upon. So it all depends on how you plan to use them, either as an overdrive or a preamp replacement. And, in fact, I wouldn't even necessarily say "plan" here. Once you've got them built, play around and see what you like best.
As a slight aside, I've used the Black '65 as a preamp replacement in the past where I had it dialed in to react similar to my Traynor YCV20's pre-amp. I've had decent success using it in situations where I've run through clean solid state amps (PAs, direct recording) and wanted to "intercept" my overdrives so they weren't trying to push something like a PA's preamp into clipping.
Q: Why is a drummer like a scud missile?
A: Both are offensive and inaccurate.