Many companies will grind whatever you want. I would say that Step 1 is to look through Melling's catalog, although they only list two cams for the 4.9L. Most cams blanks these days are made by one of a handful of companies, all of them fine. Then they hand them off to Crane, Melling, Comp, Isky, Lunati, Schrick, etc to be ground on their own profiles.
Many of them will let you spec whatever lobes you want from their list of profiles which is extensive. I usually end up with Melling for a couple reasons: 1) Dirt cheap. Like less than a replacement OEM cam sometimes. 2) Their catalog has millions of grinds already in it and I can almost always find something so close to what I need that customizing it two degrees one way or the other is splitting hairs. 3) They (at least used to) let you do some fine tuning for free. Like for instance if you found a perfect 214/222 cam with 114LSA and you wanted it on 112LSA, that's no skin off their teeth. It's just a quick 2-second edit on the grinder. I did that with a Marine cam that I used to build a few crate engines to sell. I would order some 22124 cams with a 112LSA instead of the 110 in the catalog.
Back in the day when I was doing that, they had lobe patterns. If you ordered a certain grind, they would chuck up intake lobe pattern X and exhaust lobe pattern Y, load them in the grinder and set the LSA to the spec, and grind away. Changing things up doesn't really take any more time or effort on their part. Theoretically, I could spec the intake lobe from a Dodge 440 and the exhaust lobe from a Chevy 4.3L application and they could grind it on a Ford blank.
Where you get into trouble sometimes is that you're circumventing the manufacturers' knowledge base. For instance, maybe the base circle of the mopar lobe you chose is bigger than the Ford's and you would throw off the geometry, or need shorter pushrods. There would be significant research involved, but as far as the grinder is concerned it doesn't cause them much headache to edit a few fields in the CNC interface, or chuck up one lobe pattern instead of another.
I would suggest doing some research on what other cams out there have a similar or same base circle as your 4.9L, then troll the Melling catalog for lobe profiles in those applications. You might be able to call Melling and say that you want a 4.9L cam ground with the intake lobe from a 22890 and the exhaust lobe from a 21304 (random numbers, not real part numbers) put on a 110LSA, and they might be able to do it.
Another way you can do it is to have your cam reground with a smaller base circle and a new lobe profile within a small window, given the limited meat you have to play with in the lobe. Kind of like when you offset grind a crank to increase stroke. You can get a little, but not much. Provided you aren't going wild, you can do it that way. There are downsides though, other than just needing longer pushrods. The smaller circle means the ramp attack angles are modestly steeper. Not as much of a problem with rollers, but can exponentially be cause for concern on flat tappets. You'll either run into excess wear, or you'll have to grind the ramps milder to compensate... which is not a good performance choice.
