BB shell angles help

[NBC]

hi all,

i'd like to use the geometry and fit that i've got on a current bicycle i own, so i've measured and drawn up the frame design on paper, however.....

the bottom bracket shell angles i've obtained seem to be a long way from most standard road shells

i need to obtain an angle of 59.5 degrees between the seat tube and chanistays, and an angle of 55 degrees between the seat tube and down tube

i'd like to take some advice from all you experienced builders out there, to see what's really possible !

if it is too hard to work a shell into those angles, then i'm left with either a fillet brazed shell, or creating a lug ?

thanks in advance

nathan

((sorry forgot to add, this is for OS tubes, and oval shaped chainstays))