Need a little advice, New cutting edge on 80 inch back hoe bucket.

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Have a 70 CK 580 80 inch  bucket that was likely parked with the bucket in a sand pile for many years. Bucket floor and edge rotted out, plasma cut everything away and straightened out the grousers on the bottom, had a new piece of cold rolled fitted and picked up a weld in base edge and bolt on wear edge here's the question.  How much pre bow do you put in the bucket before you start welding?  Just tacking the base edge with 5  1/2 inch long tacks has warped the edge up about 1/2 inch.   7 foot bucket and will be getting a lot of welding done. I'm planning to preheat to 400 with a lot of propane before welding and keep the temps up for a while afterwards. I can slide a bottle jack between the top of the bucket and the lower edge, tack in a small cleat to anchor everything.  Have to weld the floor in front back and sides, weld on the new base edge and everything else, planning on using innershield and the tackwelds are 7018 Thanks in advance!
Reply:I've never prebowed edges, just balanced the welds, front and back.  Is it a preformed edge with holes punched in it for a cutting edge (plow bolts?), so you can replace the edge later?
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Reply:Yes its punched for a bolted on wear edge. So start in the center and work my way towards the outside?  Looks like another suggestion was to jump ahead 4 inches and weld backwards toward the last weld to reduce the warpage as well.
Reply:The way I always did it was clamp, not tack the cutting edge on with a piece of tubing to hold it straight. Heat to about 400 and start welding on the top side, weld out on way about 4 inches, then weld out other way, keep doing this until you are to the end and flip over and skip weld on back.  You don't want to tack the edge on first or it will not expand and contract freely which will cause issues.
Reply:Gotcha, I'll remove the few short tacks and start, luckily I have a whole pile of clamps!  Cut the tacks and brace the bucket so its square, Happen to have a piece of railroad rail, wondering if that would help keep the heat in during welding, sure would add a lot of thermal mass. Will get things straight then start over from the middle out.
Reply:Originally Posted by fast*stGotcha, I'll remove the few short tacks and start, luckily I have a whole pile of clamps!  Cut the tacks and brace the bucket so its square, Happen to have a piece of railroad rail, wondering if that would help keep the heat in during welding, sure would add a lot of thermal mass. Will get things straight then start over from the middle out.