First off, thanks for all of the input guys! Exactly what I was looking for.
Bill, that's very helpful info. about the length of the muffler. That makes perfect sense. When I decide which brand to go with I'll take some measurements and get the longest one I can fit under there. All of these mufflers are tube shaped so they should all fit through the x frame nicely. I've also heard that the closer you can get the muffler to the engine, the better it sounds as well.
Chris, motor is not fixed. I was just daydreaming about what it'll sound like when it is fixed. Lol. But I think I've finally found a good block. I've been running all over the country trying to find a good one. I picked up a '54 engine and a bunch of other parts from fellow member Tom N. out in Iowa a few months back. That one turned out to be cracked too but the "price" of all of it together (ABSOLUTELY FREE!!) made it worth the trip. Got some nice parts out of that deal, thanks Tom!! Recently contacted a fellow member that advertised in the Bulletin name of Bob K. down in Kentucky. He sold me the engine out of his '53 Dragon and threw in a bunch of other parts free. Got it home a few days ago and pulled the head. NO CRACKS!!! WOOHOO!! I'm thinking this might be the one. I now own THREE 226's. Think I'll make coffee tables out of the other two. Anyone interested in one? Lol. Anyway, I got it put up on a stand last night and I'll be flipping it over to inspect the bottom half soon. If everything looks good I should be able to send it to get rebuilt in the next month or so.
To answer your last question, I will probably go with the Brockman Mellowtone. The longest one I can fit under there. The good thing about these types of mufflers is that they're pretty cheap. If I put one on there and it sounds like crap I can take it off and not be out that much money.