I was just wondering. I've seen some fords with crossflow heads and how santucci made a crossflow hybrid head for his 292 when I was reading his book. Are there any inherent advantages to a crossflow head vs a stock head? Is it worth the money?

Crossflow heads are more efficent for breathing (ie.horsepower), most foreign inlines are that way. No compromising the configuration, lengths,or routing of the individual port runners (be it intake or exhaust) since they are on opposite sides of the engine. However, the non-crossflow design lends itself to more utilitarian usage with its more compact design (carb heat for example is easily accomplished with a non- crossflow). A little more thought (and plumbing) must go into turbocharging a crossflow inline compared a non-crossflow. The turbo non-crossflow can be a very neat package (especially a draw-thru) since the inlet and outlet are conveniently nearby. Checkout virtually every vee type engine-all crossflow (easy for them-almost a necessity).
Crossflows are not a necessity-they just make it easier to make hp. Is it me or what, but it seems odd that both the Kirby-Sissell head, and the Duggan head are not crossflows. Thats a large undertaking with a lot of design time not to incorporate crossflow into their finished product which is supposed to a horsepower maker-it makes the designs of Wayne, Horning and maybe Herbert a bit more serious. As they say "my two cents thrown".

not to incorporate crossflow

Marketing decision. More changes = fewer stock parts fit = fewer buyers = more time to make the investment back.
The actual mistake in may of those (cross-flow or reverse-flow) was the chamber design. At that time very few people were paying attention to what was possible (Triumph and H-D both had hemi engines worked out by 1938), and used such atrocities at open chambers with vertical valves.
There's also a significant different in efficiency between a head with in-line valves (parallel or not) where the ports are not aligned with the bore center, and a head with the valve axis at 90° (which need not be a hemi).

IMO it is shared ports which ruin HP. Once both valves are closed during the power stroke it makes no difference which side the next stroke goes or comes from. In a conversation with Joe Fontana when he had the midget engine business he had the alility to put any head on his 4 cylinder block. The one that was labled as his was not a crossflow and I believe started life as a Duggan when Nick Arias owned the rights. He also put Ford Yates and other Chevrolet heads on them for customers. He did lobby for additional cubic inches for the non-crossflow but all engine manufacturers lobby something "extra" so they can sell more products. He told me thre was vertually no difference between one side and crossflow.
I'm no expert I just know what I like to look at..........JD

As panic mentioned, just because a head is crossflow or not doesn't necessarily mean it is superior to the other design. There are good and bad heads of both styles. It takes a really high dollar crossflow head to outperform a well prepped siamese head or Kirby 12 port(both are non-crossflow designs)head.

There are many other design considerations that complicate head efficiency: where do the bolts go, how is water distributed, how straight is the path between the port face and the valve seat if it has to go around the pushrod, etc. These are all compromises, with production cost, weight, and ease of service having higher value than absolute power.