That's looking really good!
To be honest, I don't keep track of the number of hours I put into various aspects of the car, but yes, it can be very time consuming. If I recall correctly, I think I had nearly a year of evenings after work into the frame in total. That includes boxing, reinforcing, rewelding factory welds etc tho.
Looking at your pic, the biggest difference I see between what you're doing and what I did was I rewelded the factory welds and then cleaned up the edge of my weld still leaving a seam, where as you're trying to blend the seam into the lower surface.
It can certainly be done, but that's much harder and time consuming to do.
View attachment 59217
The only portion of the frame that I deviated from this was on the front frame horns from roughly the crossmember forward.
Because these areas can be seen when the hood is open, I didn't want any seams visible. I made cardboard templates of the lower surfaces from the seams to the edges, then transferred them to and cut them out of 1/8" plate. The plates were overlaid over the lower surfaces and welded in place, then the welds were dressed down and blended in. This made for a much quicker and cleaner finished product IMO.
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Just make sure you prep the overlapping surfaces with zinc weld-thru primer or something similar to prevent corrosion from forming between the two sides before you burn them in.
I'm not sure what you're using for grinding and blending, but my "go to" tools for this were 5" 40 grit Walter flap discs on my Dewalt electric grinder, and smaller 3" 40 grit Roloc discs on my 45 degree air grinder for the finer, more detail oriented stuff.
As far as dealing with the inevitable pitting, try and get the surface you're going to weld as clean as you possibly can before hand. You want nice clean shiny metal to weld on. Dirt, rust etc is just contamination you're including into the weld. Starting with as clean metal as you can before hand will not only result in a cleaner stronger weld, but you'll get less popping, less pitting and voids, and better penetration.
(While not necessary, if it's at all possible, having the frame sandblasted first is a HUGE time saver). I had to wait till spring, but a buddy and I loaded it into the back of his truck and hauled it down to the local do-it-yourself sandblasting yard where I blasted it in about an hour for around $100.
Sorry for the long reply, but as you can see there's quite a bit to it at times!
Hope this helps you out.
Donovan
