Trying to keep the original front frame section(K-member) just makes this a lot harder to do. Go to Speedway Motors web site and look at their Gasser front suspension and frame package to see what things need to look like. The have a couple of PDF files you can look at too.
You can also search at www.jalopyjournal.com
which is the HAMB web site(Hokey ***** Message Board). Lots of Gasser info there, and lots of build pic's. I was just looking at a '55 Chevy straight axle build thread there last night.
Biggest problem with keeping the stock front frame is that the drop section in the center of the crossmember is where the straight axle needs to be causing a clearance problem unless you go rediculously high in front, cartoon-ish high.
I'm in the process of gathering parts for making a Gasser out of a '71 Vega, going to build my own rectangle tube front frame like the Speedway set up, which is like most that were done back in the day.