Tod, your business ...your call, however somewhere along the way greed has overtaken in this country on both sides of the fence (manufacturer and consumer).
With many things besides Model-A parts, both the Manufacturer and the Consumer have thought it is prudent to cut-out the Jobber/Dealer (the middleman) and take the Dealer's profits for themselves. If all of the manufacturers in our industry chose to do direct-sales, I feel this hobby would be 'killed'. My opinion is many Model-A parts manufacturers do not have the capitol to manufacture and warehouse all of the goods they manufacture until they are sold, so they rely on a dealer network to quickly pay for the items and distribute those items for them.
Adding to that, imagine all of the additional shipping expenses for each of us by us having to order from multiple suppliers. Using your cylinder head as an example, imagine if we had to buy the head from you, then we order the head gasket directly from FelPro, order the correct length studs from ARP, the head nuts from McMinn, the correct engine paint from PPG, the radiator hoses from Gates, etc. etc., ...then we had to wait for all of those packages to arrive at our homes (-while we hope something we ordered is not lost in the mail or shipped incorrectly!!).
I am going to guess that if most hobbyists had to go thru something like that, they would just say it isn't worth the hassle. At that point, you would likely sell
less heads. As it is right now, most of the better Dealers (Berts, Brattons, Snyders, -insert your favorite) do a darn good job of stocking
everything of what you need for doing a job like what I mentioned above. If they are out of stock on something, it is likely the manufacturer's fault, ...and if so it, the chances that if you ordered it directly from the manufacturer, they would tell you it is backordered too.
My suggestion is 'scrap' your idea of selling direct to clubs and the general public, -and work with the established Model-A Dealer network that will be there on a consistent basis to purchase your product when you have it available. If you want to ramp-up your production on a certain item, consider offering a SPIF to your dealers where they can take advantage of that $$ savings, and you can take advantage production savings too. Bottom line is, think hard before you bypass (cut-out) the Dealership network that most hobbyists will be using, as these dealers are the frontline for the hobby.