Well, I'll start with this: I am currently 255 lbs (down from a high or low depending on perspective of 305+) and 6'3". I bloated up after moving to OR from CO and didn't ride much for a few years. I abused the hell out of a Santa Cruz Heckler for about 6 years until it finally died this year. I replaced it with an '03 Heckler and could recommend one to a fellow clydesdale such as you, however the price is pretty high.
You are going to run into several issues at your weight: destroying wheels, hubs, cranks, obtaining correct spring rates, bending bars, posts, etc. Parts can be replaced fairly cheaply at the pricepoint you are looking at (and things DO break). One of the biggest "bummers" is going to be getting the suspension set-up correctly. It's not impossible to set up a Marzocchi with the correct spring rate (pre-load doesn't make up that much difference), but it is VERY pricey to have someone custom wind you springs (if you can find someone to do it). Getting the rear suspension correct at your weight is even more maddening and having a 5 or 6 inch rig with the pre-load maxed out and still having 50%-75% sag rides like [censored], trust me. I wished I had a hard-tail while I was losing weight, it would have been so much less hassle and you get better components for the same price, generally.
The best idea, from my perspective having been there and still being a lot bigger than the average riders I run into, (and you already indicated you are going to) is to loose some poundage while riding a used (take a serious look at "pre-owned" bikes for now), save a few bucks over the next year or so and then drop some coin on a FS bike later. Ebay and some shops can have killer deals on bikes a year or so old and in good shape often with upgrades from OEM. Konas are OK, Norco makes a couple of good hardtails, SC Chameleons are good (I gotta throw in an SC plug), Marin is still alive and kicking butt, sort of. Ride a lot of bikes and focus on wheels, forks and cranks for now. Derailleurs are easy and cheap to upgrade later. Good luck bro and welcome back. I'm sure you'll be addicted again soon and proudly showing off hard earned skabs soon!
I'm even cutting wwwaaayyy back on the weight lifting these days to loose more pounds and hopefully ride a little closer to the skinny folks up some climbs and carve the corners a little faster on the way back down. Now that I'm not playing ball anymore I don't need the extra mass, you know? Good luck and let us know of your progress! Take care and ride well.
K.
