This information is from HD Tech Tip #34 and #37.
HD Tech Tip #34 incorrectly listed the part numbers for the two new retro oil tank kits as 62472-93, and 62473-93.
Just correcting the records, the correct part numbers are listed in Tech Tip #37 and shown below.

There were two retrofit oil tank kits available for earlier Sportster models. The oil tank will retrofit to all 1982 to 1993 Sportster models, except the XR-1000.
All earlier tanks were obsoleted and replaced with these two kits.

Corrected part numbers per TT-37:

• 1982-E1987 (62482-93) with flared brake lines.
• L1987-1993 (62472-93) with banjo brake lines.

Later, the kit was updated with new part numbers. ( Click Here to download Instruction Sheet #J00572)

• Kit (62482-93A) is designed for installation on 1982-E1987 XLH models.
• Kit (62472-93A) is designed for installation on L1987-1993 XLH models.

Article by Benton of the XLFORUM ¹⁾

J&P carries a battery tray (350-065) for around 100 bucks. The tray fits the 1994 style tank then purchase a 1994 style tank. The tray mounts to the oil tank with three bolts instead of two, which is what makes it more stable and keeps it from vibrating.
The lower two holes are also spaced wider. The oil tank from J&P only comes in chrome.

The fit of the tank is excessively tight because the oil tank outlet (1/2”) lies just in front of the main frame support, but it will fit.
The top of the tank is against the frame though which makes them solidly mounted. The battery tray also fits the 97-03 oil tank and this may or may not be a better fit.

Here’s some comments for those considering this replacement. The new battery tray comes alone, so you’ll also need some new hardware:

• (1) 1/2“ x 3/8” brass reducing tee.
  This is because the new tank does not have a separate outlet for the drain and you have to split it off the tank (feed) outlet.
• (4) rubber studs for mounting the oil tank and battery tray along with 1/4” nuts and washers.
• (2) fender washers for the battery rubber stud to space it out appropriately.
• (3) 5/16” course threaded bolts to mount the battery tray to the oil tank along with washers and lock-washers.
• New hoses and clamps, 3/8“ and 1/2” for the oil lines and a 1/4“ for the vent line.
• (1) 1/2” bolt to plug the oil line drain and a hose clamp. You need one with a shoulder or it will leak. (you can cut 2“ inch long bolt down to do this)
• Blue Loctite
• Cardboard to line the tray with (it will outlast your battery).
  It’s easiest if you cut the cardboard before you install the tray. Paint it black if it bothers you.
• (a new chrome ignition cover to match the chrome tank along with 3 new well nuts. You aren’t really going to let the bike go out with mismatched sides are you?

Routing: You need to put the 1/2” hose on the tank BEFORE you mount it, as it is a close fit against the frame.
The rubber studs will flex to accommodate this and the mounting holes, but you’ll have to push them some to do so. It’s a very tight fit.
Once you put the tray on, it may be somewhat forward of the rubber stud. Fender washers on both sides of the rubber spaced it for a solid fit.

Route the transmission vent line and the positive battery cable behind the tray between the bottom two mounts.
The negative battery cable goes forward of the mounts. The oil lines run under the starter. The vent line can run outside the starter.
The tank feed fitting / line is 1/2“ that runs straight to the tee with the 1/2” oil drain line on the other end and the middle attaching to the 3/8“ tank-to-engine oil line.
There’s no drain plug on the new battery tray so you’ll have to use a bolt and zip tie the drain line it out of the way.
(The 94 year bikes started putting this plug on the right side of the swingarm).
The oil lines are actually neater with the new tank setup than they were before because all of the fittings are on the bottom of the tank.