Frame selection...
 

Which kind of bike tends to put a greater percentage of weight over the front wheel?

uni- cycle ?
sorry couldn't resist
I would presume it has more to do with your position on the bike than the design of the bike ie TT low profile

recumbents sometimes do have a lot fo weight up front.

My answer would be bikes with a steep head tube angle like some racing bikes, or touring bikes where a lot of luggage is carried in paniers up front.

Yes, this question is related to my other questions in my search for info on converting a common bike to an ebike. The issue of weight distribution keeps coming up. I must be careful...I have a tendency to be a perfectionist and end up getting nothing done....you know, I would be a perfectionist...if I could do it without making mistakes :)

there isn't a huge enough difference in most production frames within a given size or genre to cause more than a few percent change in weight distribution. Some more details about your plans might yield better advice. What ebike system are you considering and most importantly where do you propose to place the batteries ?

Speaking of e-bikes, have you looked at the stokemonkey? Seems like they have worked out the needs of such a package.

I once found a cool e-book on powerbikes, which are bikes that one continuously pedals, but they are driven by a motor not the pedals. The pedals, and other stuff like braking, charges the batteries. Really interesting concept, though there is a motorcycle class called powerbike, and I have never been able to successfully search out the e-book again. :(