Lightening your K frame

I'm with you on reworking the stock K frame and those thinking they're going to shave a bunch of weight by replacing the stock K frame with a fabricated piece made out of tube probably haven't picked up one bare, much less actually weighed it.
The factory piece is a pretty tough act to follow with the basic structure made up of two light weight sheetmetal stampings spot welded together at a pinch flange. The weight of the steel making up the pinch flange can't amount to much, not much more than a few ounces at best, and probably contributes slightly to the overall rigidity of the piece.
While trimming the factory pinch flange to just a vestige large enough to weld solid wouldn't save enough weight to compensate for the steel you added beefing the K frame up, with the added gussets and everything welded solid it probably wouldn't hurt anything either, and would be beneficial to component access. Doing so might even allow you to lengthen the engine's oil sump slightly.
My buddies around here and I have been thinking along those lines also. I won't get into things like universal motor mount pads to change easily between engine families or moving the steering box mount ahead to accommodate my C body steering column, but you can imagine we're giving some thought to stock K frame mods.
Dick Ross (Firm Feel) has been beefing up the stock piece by welding all the seams solid, gusseting, and adding a skid plate for years. He will sell you the coupon kit if you want to do it yourself. I'll ask him what he thinks about eliminating or minimizing the pinch flange next time I get over there.