Because I am looking for a 30's or so fork for 27's or 700's. Similar to a BSA track bike fork from the 30's with the crown lug with the squareish window cut out of the lug on the sides..

seperated forks are hard to find I'm finding.

Especially on "older" bikes, and you are talking the 1930's, getting a set of forks to fly with the frame will be difficult. You don't just get a front fork and slap it in. What is the correct steerer length? What thread size? Is there an index notch/groove for the headset spacer? What is the desired rake? Brake bolt allocation? I would not discourage looking for one, but if one cannot be found that is proper for the bike...

I would bring the frame, the headset, and the wheels to a good framebuilder. He/she could easily modify a forkcrown, or even dig one out of a "super secret stash" and build you a correct front fork with the proper rake, look, and threaded portion of the steerer for your frame.

Unless somebody just happens to have something like this sitting around, getting a front fork custom made should be very reasonable and correct for the bike.