I had brand new locking oem style in place when I put the HO350 in my 67, one separated the rubber after only a year. I then put a pair of Prothane mounts in their place since no good reliable replacement was available at the time.

Have to say there was no real negative difference in feel. Felt just as smooth all round, with maybe just a firmer telegraph of power on quick acceleration. My 496 has them with a semi rough, sharp idle, doesn't shake or rattle the car in any significant way. 

I don't mean to hijack with this poly talk, but other than the non stock appearance, I don't get the resistance towards them. But regardless, good luck on your search for good new or nos oem, I'm sure they are out there.

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I love those balancers. Makes it so easy to adjust an engine and trans in or out in one peice a little at a time. One clearance trick I learned was to raise the rear end up as high as practical. It lowers the rad support a couple of inches.

Thanks Don. I went ahead and ordered Summit's mounts.They are urethane in black and grey. I also got the drop down fuel line kit for the 1406 carb. It comes with a filter.I ordered black.I do like a filter I can see into but small ones for hard plumbing seem pricy. I ordered a couple of pump to carb lines as well. I will choose the best fit and crop it to fit the new filter set up.I can get a correct 2 bbl hard line but I'll get that after I find the correct intake and carb. I've picked up a few other tidbits..spark plug wire holders,torque converter seal, new throttle spring etc. I think I will replace the valve guide seals while I'm doin this.O-rings and umbrellas I think...I used to do that somewhere in another life! Meanwhile I scratched around in the grime and have determined that my motor is 283 manufactured late 62 and is the original engine for my car. The heads are the 60cc "896" castings and are dated coded identicle...Dec 62. My tranny is a first version aluminum case unit with the correct tail shaft for 63 Impala SS or Corvette or in this case my Canadian Poncho! The number on the pan indicates Cleveland Nov 14 dayshift. The plate with converter seal in it shows Oct 29 62..Now I feel confident that this is all original to the car stuff except for the 2 gear ratio tag thing on my diff..It's a correctly coded Canadian "P" case with 336 gears but for some reason there's a 411 tag on it as well...Think I'll leave it on...  The picture showing the t-shaft shows a piece of exhaust pipe the correct size with a washer welded on. I slipped this in and didn't spill any dextron...

I've got the valve covers,pan,and timing chain cover off and popped out an expansion plug. The block is very clean in the water jacket area.I see that the drain plugs have been out so it's probably been flushed out once or twice. There are 4 newer rocker arms and nuts..It seems to me that somewhere long ago I had to change 1 or 2 because they broke right where they rock....I haven't removed any yet but the springs seem so small that I'm not sure if umbrellas will fit in there! The oil pump is original and the screen is virtually spotless. The timing chain is also original..the pics show the stretch.It was contacting the cover on the lee side around 2 oclock.

Part of this exercise for me is learning tech stuff like sizing and posting pics on this or any other forum. My son who lives too far away from me is a wizard at it, but distance and time(he has a family) get in the way. Non-the-less I am learning albeit somewhat slower than I used to....The main seal was almost part of the block. I had to let all of the main caps loose to get that bugger outa there. It's done..timing gear and hub sleeve and cover done.I'll get everything together and then give it a rattle can face lift...Carl, my paint choice is not what I like but "they" quit makin my favorite ...Valspar 200 Chevy Orange. Lots of work to clean all this manually ... a rebuild would be easier ... trying not to get too many crumbs in the internals is painful. The photo of the blocks of wood is what I did to stop "shock" when I beat the front crank hub(sleeved cause of the groove) back on with a piece of brass pipe and a chunk of wood

This has to be my most interesting find...