All 1st generation sbc balancers interchange. Except the 400, which was externally balanced. It don`t matter where the timing mark is, as long as the balancer is correctly matched to it. If it were I, I would install a 8 inch balancer from a 350 chevy heavy duty application with a timing mark at the 2 o`clock location. Then get a cheapy aftermarket bolt on timing tab that bolts up at the 2 o`clock location on the timing chain cover.
Whichever balancer you use, make sure it fits the crank snout tightly.
If I`m not mistaken the early 70`s 350`s used the 2 o`clock position which is the easiest to read. The later timing tabs were at the 12 o`clock position making it a pain in the a** to set the spark timing.

 

Whatever damper you get, I would check your TDC and zero the timing mark.........Also....You may want to get your crank drilled and tapped for a bolt to hold that damper on while you have it apart

 

I agree w/DV that the 2 o'clock damper will usually be the easiest to find, and that's what most all (at least that I know of) the aftermarket timing tabs are made for, except for possibly some adjustable timers.

Your engine originally came w/a 2 o'clock damper, many of which were 6-3/4" diameter units. 327's ALL used this damper TDC line position- there wasn't three different timing mark positions for the 327, there are at least three different positions for the SBC in general, though.

There were 8" dampers used on some HiPo 327's from the factory. Most were 6-3/4", though. I wouldn't hesitate to use either on your engine- as long as it was new or like new.

The following is from another post I made on this:

There are several different dampers. Both the diameter, thickness and the placement of the line on the outer ring of the damper can differ. So you need to know what you have, to know what tab to use.

The three most common locations for the timing mark on the damper:

The pre-'69 damper has the TDC line on the outer ring at the 2:30 o’clock position- or 2º before- (i.e. to the LEFT of the keyway, looking at the front of the engine) the keyway centerline. The keyway is seen in the ID of the damper.

The damper used from '69 to mid-80's has the TDC line at the 2 o’clock position- or 10º before the keyway. You'll find that aftermarket dampers are the 10º type, as are the bolt-on tabs sold in the aftermarket, unless they're adjustable.

A third timing mark was used from about 1978 to about 1991-'92. It is at the 12 o’clock position- or 40º before the keyway. This damper uses a timing cover that has the tab welded on at about the 12 o'clock position.

If you're unsure, or just want to check the accuracy of the tab/mark for TDC, DETERMINE TDC and MAKE A TIMING TAPE will help you to see for yourself.

 

Thanks fo the info! It is so nice to be able to come here and get good information. Poncho, I have my crank at the machine shop right now to be drilled and tapped for a bolt. I just didn't like the idea of not having one there. It looks like I'll just use the timing marker that I have already, and buy a new 8" harmonic balancer. Thanks again for the help!

 

Thanks fo the info! It is so nice to be able to come here and get good information. Poncho, I have my crank at the machine shop right now to be drilled and tapped for a bolt. I just didn't like the idea of not having one there. It looks like I'll just use the timing marker that I have already, and buy a new 8" harmonic balancer. Thanks again for the help!

Unless the timing marker you have is for the 8" balancer, this won't work. The 8" balancer will not clear the marker made for the smaller 6-3/4" diameter balancers.

I'd remove the factory marker and use a bolt-on marker for the 8" balancer. The bolt-on markers are really inexpensive, about $5 or less for the simple stock type bolt-ons.