Help out a poor Aussie!

Hi Guys
Just wanted to see if anyone could help with some advice on "old-style" Dove alloy heads.
I have what I believe to be a 390FE, there is no code on the block to identify it apart from "61 DIF", the date code with the first number obscured and a hand-stamped number on the front of the block near the RHS head (RH12040). The heads that are currently on there are cast CA8E which matched the story that the motor came from a '68/69 Galaxie sedan.
Anyway, the intended use is to replace the tired 289 that is currently in my '66 Galaxie, it's main duty will be cruising but I would like it to be a tough street motor without being an unmanagable monster. So far I have the motor and a bunch of spare motor parts, a Holley single-plane manifold (Street Master? I dunno it's buried under a bunch of parts) and some dress up gear. There is a C6 waiting for the go-ahead at the trans guy's place.
The plan is run straight LPG (I think you guys call it Propane) because fuel is pretty expensive here and LPG is about 1/3rd that of petrol, my mechanic recommended the single plane manifold for the LPG use.

Anyway, there is a local importer who gets in rare (in Aust)second-hand engine stuff and can get a set of "old-style" Dove heads for me for a good price, $600 Aust.

Does anyone have any experience with these? Is it worth my while for the performance increase (if any?). Are there any known problems? Or should I put the money into a good head-job on the cast iron heads?