If there were blueprints readily available for a frame kit half the guys in here would already make one.
Is this swap easy? No. At least not as easy/cheap as everyone that hasn't done it thinks it is.
Can it be done, and on a budget? Really depends. But the more I look into it the more "little shit" that I haven't heard about before i find out that it requires. All that "little shit" really starts adding up, both in time and money. Just my .02

Don't jump into something unless you have it all COMPLETELY figured out/mapped out from day1.

So 270hp in a turbo 4 is like what compared to a 405hp v8? Is that 270 off the line at a hard launch? I'm gonna be a real launch pussy with this car, hell I am now with the turbo 4!

I think you should plan to go with the ford rear end from the get go. I just wouldnt want to have to baby the rear end all the time. And already mentioned is the question of how the heck you plan to hook up the transmission side of the PPF to a t56 transmission? Obviously it would not be an insurrmountable task or anything, but it will require cutting the PPF and making a custom brace for it.

Beyond the engine and transmission mounts, its mainly fuel delivery, wiring, throttle cable (or dbw pedal), and driveshaft. Then there is the issue of getting a signal to the spedometer which is an electronic signal from the t56, so you will need to install a custom gauge for that at least. Dont forget the exhaust either.

Also I think that on the truck motors, if you install an LS intake manifold, the throttle linkage interferes with the pulleys somehow and this can be solved by either using drive by wire or LS1 pulleys

I was comparing it to your 285 (really 310'ish) hp motor Where did 405 come from?

The thing with the rear is that a 300ish V8 in this case probably makes something like 330ish TQ, where a 300ish I4 is going to be under 300TQ in most cases. TQ breaks things.

Then again, I'll bet that most if not all T56s have a less agressive 1st gear than a Miata trans, and that will actually spare the diff a bit of pain on a launch. I doubt a torsen would handle it though. An open 7" diff might live longer due to more wheel spin, which takes some stress off, assuming there is not wheel hop to contend with, which there may be. Any wheel hop at all would probably grenade any stock Miata diff in this case.

An RX7 unit might work though, and be easier on fab. Stein's solution is probably the best from what I can see.

405 came from an estimate of the output after I swap a cam and intake / throttle body. You didn't think I would put that heavy block truck motor in there and leave it factory did ya?

A Walbro 255 should be just fine, lots of F-Body guys use them with bolt-ons. So one of those in the stock tank is a win.

I would not bother replacing the heads. 5.3 heads are pretty darn good as is. Now headers, intake, and a cam/valve train, thats a good idea. GMG makes a hotter version of the 5.3 and all they did is some graphite coating on the pistons and a slightly hotter cam and the power went to an official 320, whcih means its probably more like 340 in good air.

Note that many thunderbirds do not have traction-loc rear diffs, and even some of the 5.0 and 4.6 disc brake tbirds have open 8.8s. Weird I know, but true. When you go to rip one out of a car, look at the door jam, and take a list of axle codes with you. They specifically designate LSD or not. For instance, almost all 97 tbirds with the 4.6 will have a w5 axle code, which denotes it is a limited slip rear diff.

Also consider what you're doing for axles, are you making them from a mix of tbird and miata, or having some made. Price point really hits home here. You can make your own with a set of tbird axles and miata axles, a bar, and a welder. As long as they are true and straight, the center where it is cut will hold.

LS1 LS6 5.3 NEW BLOCK ALLUMINUM GM CHEVY : eBay Motors (item 290413909277 end time Mar-21-10 18:47:47 PDT)

Might be handy :)

Or, since I am totaly awesome (and I cant do this project myself any time in the remotely close future):

http://cgi.ebay.com/ebaymotors/LS1-L...item439e04951d

Whole Al engine for 700 plus shipping. Tasty.