Do you know which oil pan was on that car? It sounds like it was missing the rear acceleration baffle like the early C body oil pans where made stock

This was around 1983 I *think* it was a 402 pan but can't be sure.

Anyhow, do you think I'll be OK with the current pan and 7 (or 8) quarts? I know a lot of oil goes up top due to the grooved #4 cam journal.
Is it difficult to put in oil restrictors with the engine assembled and in the car?

If you used the stock motor mounts on the OEM 383 A body cars made form 1967 to 1969 the 402 pan will hit the steering cross bar, been there done that
The original pan for the A bodies where stamped 890 I think, not sure if they where for all 3 yrs or not though
I used the 1965 to 1969 C body pans and welded in acceleration and deacceleration baffles in them they will hold 5 quarts easily, some guys have ran them with 6 quarts in those pans also Those oil pans look a lot like the stock 1966 to 1969 Street hemi oil pans also, one of them may fit also I never tried one of them in A body due to there resale value
As far as adding oil restrictors you can add them into the oil passages in the heads, I would remove the heads and drill and tap that passage for either a #6,#8 #10 or #12 thread size for using a blank brass set screw in one of those sizes, which ever fits the best I use a .042 drill bit size in the set screw to make them flow oil that size works well on roller rocker, I would use a bigger hole for non roller rocker though, probably around .080
I normally restrict those passages in the block, while building the motors I don't remember what size set screw to use now though
I use #6x32 blank allen head brass set screws in carbs to restrict the fuel delivery to lean them down in the idle and transition fuel delivery circuits

I had bought an actual DC big-block K frame (remember them?). Car was a '70 Valiant. It cleared.

I'm still kicking myself for selling the car in 1991 when the USAF transferred me to Ohio and would only pay for one car to be shipped. The mild 383, OD 4-speed, 8-3/4, Centerlines... AND a pair of real 383 A-body manifolds in a crappy '76 Valiant. Worst part is, I only got $700 for the whole thing. The manifolds alone are worth more than that now!

Anyhow, I'm eventually going to have a half-decent pair of aluminum heads... plan is to send my bare Speedmasters to Dwayne and have him go over them and do a stage 1 or 2 port job. Once I have the money that is While the heads are off, though, that would be a better time to address the oil restrictions! I'm not planning to pull the ported iron heads and put them back on since they're probably mediocre at best...

Heads are the key to power along with the exhaust and intake system