389 engine ID help?

Hello again,

This one is a little tricky for me, so I'm asking for some advice from any experts out there?

Trying to accurately identify the engine in my '61 Bonneville, I've followed the Hagerty "how to identify" article, and referenced both the PontiacPower.net and Wallace Racing lists. If I have the information correct, it is a 1959 block (code #: 532000) fitted with 1960 heads (casting #: 536109). It is mated to a Hydra-matic - tag reads P-60-200684, & a Carter 4BBL - tag reads 4242S, with L6 PD underneath (Carter's list says it's from a '67 400?). PCV is at rear, it has 2x welch plugs each side of the block, starter is fitted to bell housing.

If this is the case, there won't really be any (easy) away to ascertain the actual output of the engine I presume?

For practical purposes I guess I would tune it as a '60? Tune up specs that I've found don't seem to vary at all (points .019", dwell 30, timing 6º BTDC).

Any info or guidance you may be able to provide will be helpful, thanxx.