Thanks to everyone for your suggestions and comments.
To manufacture a new part, it must have a positive ROI (Return on Investment). The parts we manufacture have positive ROIs because they appear original, have hidden features to correct design shortcomings, and there is a high demand.
Many of the suggested parts (synchromesh transmission, intake manifold for Model B carburetor, F100 steering gears, higher 2nd transmission gear, larger carburetor, and vibration dampers) are already in production by others.
Some parts (automatic transmissions, overdrive transmissions) would be too large to fit into housings and maintain a stock appearance.
Other parts (two-up and two-down crankshafts and camshafts) will never have a positive ROI.
I have to wonder about the cast-iron high-compression head for a Model T. I see the aluminum ones in Lang's and Snyder's catalogs, but I wonder why they don't offer a cast-iron head.
Some parts (Model T and V-8 cylinder blocks) would take too much of my time and would be too expensive to have me direct other engineers.
I have no interest in copying a stock Model A cylinder block because, other than better material, it would have the same shortcomings as an original cylinder block. Original, Burlington, and Scat crankshafts all will have a fatigue failure at the #4 connecting rod journal before a cylinder block failure. The New Engine patterns for the cope and drag, and core boxes for the water jacket, and the exhaust ports could be used to save money. All other cores would require new core boxes. There would be no ROI because it would take too much of my time and would be too expensive to have me direct other engineers.
In response to the poster who wants me to change the design of the new cylinder block to relocate main bearing studs 1 and 3 and eliminate oil leaks. The stud locations cannot be changed because they are in the same place as the original studs, and the only way to machine the seat for the castellated nuts is back-spot facing. Every potential oil leak path is discussed in the Builder's Guide.
Egge pistons are often "out of stock" because they are unable to make them fast enough to keep up with demand. I have a piston design that is lighter and stronger than the Egge design. Lighter reduces connecting rod stress, and makes the engine more responsive. Stronger allows higher RPM. If we can produce pistons for a competitive price, we will offer them.
I congratulate Arnold for making a ceramic/carbon seal water pump, but I don't like that it doesn't look like original. The water pump I designed will look like an original Model A water pump, and I have sent step files to my son Jesse for 3-D printing.
The following pictures show details of the new printed piston.