Jeff, That' right, in mid-1958 there was a 430/400hp option, 6v not 8v, 3 2-barrels on top. Very few made, estimates are 100-200 cars total. 1958 only. Much more common was the 1958 430/360hp 4-barrel, and it was, well, its been called the "Bulldozer" and I agree. Nearly the same for 1959. My dad also had a 1960 Merc, 430/310hp 2-barrel. I still remember riding in it. BIG. Not real fast though. Later on we had a 1958 Merc 430/360hp 4-barrel, HUGE difference. If you've been in a 1969-70 Ford 429/360hp Galaxie or Marauder, the early 430 Bulldozer is just about that strong - we had all those cars bone stock back in the day. I don't know why Merc cut the 430 down to a 2-barrel in 1960. There was kind of an economy binge back then - recession in 1959, little economy cars like Corvair, Valiant, Falcon, Comet coming out, etc, but who wants an "economy" Mercury???? Merc dropped the 430 incher after the Merc bodies got smaller in 1961, and by 1962-63 Merc had the 406 and 427 engines - MUCH better. My dad built Mercury cars on the assembly line from 1952-1974 so I know them pretty well. He knew them VERY well.
Hope you found your answer! The 361/303hp Edsel came with either an Autolite 4100 carburetor, commonly called a "shoebox" carb cuz it fits in one, or a Holley 4bbl. The 4100 Autolite was used from 1958-1966 on almost every Ford v8 ever made. Just about any of them will run pretty decent on your 361. You don't really need the 1958-style unless you're going for all-original trophy meets. Any Autolite 4100 carb from a 352, 361, 390, 410, or 428 Ford will run pretty good on there. They are one of the best-loved carbs ever and very trouble-free once rebuilt with new floats & gaskets. I'm trying to find out what SIZE Holley came on the 361/303 which is how I found your post. My guess is either a 450cfm or 550cfm but not sure which. Again, any small Holley 4150 or 4160 style 4bbl will run good on there, either 390cfm, 450cfm, 550cfm, even 600cfm. In my experience, ever since 1974, Holleys are a lot more trouble and eat more gas but they are the fastest carb out there, if that's your goal. Some of the Ford 352/300hp cars even came with a Carter AFB in 1958 (now the Edelbrock Performer). The linkage will be a little different but an Edelbrock Performer, either 500cfm or 600cfm, will also run good on your car and are also very trouble-free. Good luck!