New 8/12 over 4/12 Want to make my own trusses

[wet5]

I currently have a ranch style log home (1976) that needs new shingles. I have several problems, 1) it has a 4/12 pitch with a vaulted ceiling on one half and trusses on the other. 2) the vaulted ceiling side needs more insulation, 3) I think an 8/12 roof would look much nicer and I want to put a 90 degree porch on the front, currently it has a 8 ft overhang type porch the full length.(48') The wideth is 28'.

Since the current structure is solid with not water damage etc. I would like to hand frame 2x6 rafters at 8/12 over the current 4/12 roof. How do I figure how often I need to put brace members between the 2x6 and the old roof? I priced out scissor trusses 5/12 bottom 8/12 top but they want $100. bucks each. the 2x6 would cost $40. plus any bracing, which I have pleanty of slightly used 2x4's for braceing material.

Am I all wet? With a 2 foot overhang it seems simple enough, if I can determine how much bracing I need on each side of the truce. Any thoughts or help? Thanks Tom

[colonial carpentry]

Stick framing with 2x6> there are collar ties that need to be put in @ one 1/4 of the length of the rafter,so if the rafter is 12-0 you need to come down from the peak at least 36" to get a functional collar tie.I would come down to about the 48'' mark and flatten it out there>>>>>>collar tie every other or every rafter . Go 16"O.C for your 2x6 rafters.The other issue is your 24'' overhang,@ a roof pitch of 8:12 your eaves will be 16" below your plate height.With trusses the eaves does not drop but 6'' below your wall plate.