Hi Paul. All the best on the frame off. I am just in the process with a Spyder chassis.
Sean at Spyder sent me a complete list of parts with pricing that they routinely put in a frame off, which I found very helpful to sift through. Most of the stuff is on their site, but the list was a lot easier to go through. I placed a pretty big order with them as it was easier to get all the required stuff shipped to Canada in one steel box large enough for the chassis; everything else fit easily around the frame. If you are located in UK this is less of a consideration. Anyway, the list includes pretty much every perishable bit attached to the frame.
I see they list brake lines sized to fit, which could save a lot of hassle. They run slightly different than your stock frame, so new is the way to go. I didn’t go with them as I was unsure if they had them for a Federal car, and kinda had the order finalized when I saw them. I did get new flexible hoses to the calipers.
Some of the stuff I went with included the full front & rear suspension, steering rack, brake rotors & pads. I think front & rear shocks from Spyder are Protech; he may be able to supply alternatives. I believe the bushings (that were installed by Spyder were poly, but you can confirm with Sean or Andy. Sorry, I don’t have experience with them yet, so not sure of relative merits vs. Koni, etc. I went with the adjustable rear wishbones, which seemed like a good idea.
You may want to consider a five speed transmission from Spyder. I have not installed it yet, so no reports of difficulties. I believe the final gearing in top will be similar to the 3.5. Spyder has a complete parts list that goes with their five speed including drive shaft, clutch, starter motor, etc.
One thing Spyder offers that I did not fully consider is their 14" Minilite wheels. Andy explained this allows you to get readily available tires that provide the same rolling circumference as stock. I think I figured I am loosing about 5% on final drive just from the lower profile tires I could get for the stock 13`s. This is a good portion of the gearing change you get from the 3.5 diff. This might be an item to talk over with them.
I went with the stock diameter springs, but now understand they have smaller diameter which provides more selection for wheels & tires.
I am upgrading to solid shafts, but went with one`s from a NA supplier. Views are mixed on them, so check the archives.
Other items while down to frame I am doing include radiator, stiffener for the diff, wiring, and various interior trim.
HTH and keep us posted. I have found this site great for keeping my enthusiasm up, 'cus it is a big job! Seems to be quite a few folks doing this job this year.