base2 

Plus one on RattleCAD. It is a really comprehensive program with a steep learning curve.

Don't be afraid to have or experiment with longer chain stays than is commonly available on commercial bikes. Moving the axle back has the effect of moving the center of gravity more central between the wheels. If you intend to sit more upright than not or you have longer legs than an average person, keeping the cg more central (is more towards a 50/50 split in distribution) will counter any front end lightness that can occured when you are basically sitting over the rear wheel where a longer legged person would be at (hypothetically) 90/10 or 80/20 or 70/30 or whatever. The net effect is a more balanced/proportional bike for the intended rider.

The cool thing about designing your own is making a bike for you and you alone that is proportional for your personal dimensions so you own a bike that rides like it should. I can't stand it when someone gets a size 61 or 63 or 65cm bike and all the builder did was make the head tube & seat tube longer, keeping the wheel base the same. Cheap & looks like a circus bear on a childs bike. Silly. You have the opportunity to scale a bike to your proportions...Why not use it?

I'm the opposite of you. 31 inch inseam but 72 inches tall. All torso & arms. Long wheel base mixtes with 58-60mm of trail is what I've found ride best for my tastes. I'll never buy an off-the-shelf bike again.