Howdy.  I got my license in this car in 1968.  Bought it from my grandfather.  Have driven it many miles and now I need to consider engine work or replacement.  It has a 389 rebuilt in 1985, bored 30 thousanths over.  Now have oil consumption many years later.  It is not a hot rod but road car.  Excellent driver.  Many modifications.  Currently a restored.  

Trying to decide whether to get engine work or just replace engine and transmission.  Currently looking at  GM 383 small  block or LS3 kits.  Although I have done most of the work on the car up till now, I will need mechanic help either way.  Any suggestions or advice would be appreciated.

Love to see what you do with it  

Welcome 

it really depends on how much money you want to spend and what your plans are for the car.

If you fancy saving money and enjoy how she drives , rebuild the factory 389 and drive her 

if you want a race car, stick  a LS in her 

swapping the motor and transmission will cost you as nothing LS bolts straight into a 64 

everything from motor mounts trans mounts gear shift electrical will all need to be custom made to suit 

hence $$$$$

and if your not doing it your self 

expect to pay 

Hope that helps ! 
having said all that , we are here to help if you fancy doing it your self 

cheers 

Thanks. I have looked into the LS3 kit option and 383.  It is hard to find a mechanic that knows their stuff and willing to do the work.

You will need someone who is used to doing restomod work on classic cars since custom fabrication is almost guaranteed with a LS swap. Not so  much with the SBC unless it is fuel injected.

I concur with Kiwi. The biggest two factors will be how deep is your wallet and what you plan to use the car for.

I have a '72 Lemans convertible with a rebuilt 455 (its a 462 now because it's bored .030 over). I am good driving this car across the country. My only regret was not installing a 200 4R in it to get overdrive (the 200 4R bolts up to Buick-Olds-Pontiac motors without an adaptor kit). vs. 400TH that I have currently. So having a cross country cruiser is very doable with the stock 389 and would likely cost a lot less. Granted, it won't be 500-600 HP screaming demon an LS3 could be, but unless you go to the track, where are you going to use all the HP anyway?

Great help, thanks.