$7000
If u still have money left over... do Tq Converter A4, Nice Clutch M6
and with new found power at least get subframes so u dont endup bending ur car.
then relace **** as it brakes... rearend tranny etc...

If you want to keep things from breaking start with rear end roughly $2200. new drive shaft $400.upgraded trans and converter or clutch if m6$2000. This should leave enough for stuff like an air lid $120 catback and y pipe $500 headers $700 lca's $150
all this is rough estimates off the top of my head so you can up or downgrade as you like.
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Judging from what you want, and how you want to do it, it seems you should build the drivetrain and chassis first:
-rearend
-transmission
-clutch or convertor
-driveshaft
-subframe connectors
-lower control arms
-drag radials or ET streets
All the power in the world won't do you a bit of good if all you do is spin and twist the car up! (Unless you are looking for speed from a fast roll only)
Also, would stay away from "already built" cars - generally they have seen at least some amount of abuse and will put you up on the jack stands like you talked about. Unless there is a dirt cheap bargain worth going over with a fine tooth comb.
Just my 2 cents...
If it was me and car + $7000
A4
I'd skip the 12-bolt because often the rear will hold up much better with the A4. I would get 3.73 gears.
~$600 gears & install
~$400 Nitto DR for the rear
~$50 drag bag for rear
~$250 BMR panhard (adjustable) & LCA's
~$200 Subframes
~$1200 converter and install
~$100 Lid
~$150 Fast Toys Ram Air
~$600 LT headers like Hooker etc
~$150 offroad pipe
~$50 cut out
~$200 used SLP dual/dual to keep the noise down
~$100 Lid
~$500 for LS1 edit for gears & tuning
~$275 Atap
This leave ~$2,200 which I would hold on as a nest egg for that heads and cam package.
For M6
~$2500 for 12-bolt and goodies,
~$400 slicks
~$250 BMR panhard (adjustable) & LCA's
~$200 Subframes
~$1000 for clutch replacment
~$175 Pro 5.0 shifter
~$50 shift light
~$100 Lid
~$150 Fast Toys Ram Air
~$600 LT headers like Hooker etc
~$150 offroad pipe
~$50 cut out
~$200 used SLP dual/dual to keep the noise down
~$100 Lid
~$500 for LS1 edit for gears & tuning
~$275 Atap
$300 left over
just an brainstorm I'm sure I left stuff out
A smart guy once told me to build a hotrod drivetrain from back to front. So with that in mind I would start with a 12-bolt, then driveshaft, then clutch (I'm assuming M6 because that's all I'm really familiar with). Then I would focus on suspension and brakes. Only once you've squared away all that, then worry about the engine

With my daily beater a 91 RS which I
most of the time, I'm slowly upgrading it. Starting with suspension and brakes, next driveline and last will be engine. 





