Let us know how it works out. You should be able to tell right away after installing them.

My old umbrella seals slid much easier than the new ones on the stem so maybe new umbrella seals will help, but seeing as I already have the rocker cover/rockers off and seeing that valve seals are pretty cheap - it wont hurt to use positive seals.

Positive seal fails when the stems rock back and forth, because they are attached the the guide and to the rocking stem.

Most of the oil comes down from the retainer, which is why umbrella seals work so well. They dont' rely on a seal to the guide, they just ride up/down.

Sorry, can't remember which seals they were but when I get back next week will check the invoice to see if they are ID'd.

DD, not sure on why you think the posi seals use more oil etc? They are a positive seal around the valve stem (and guide) so actually help prevent nearly all oil from being sucked down the guide. I know from 1st hand that my engine went from smoking the shed out if left to idle for any length of time to no smoke at all after having the seals replaced (and the guides weren't touched).
The umbrella types have a bad habit of riding up the valve stem until they sit just under the retainer, thus doing sweet FA to stop oil being sucked down the guide.

The positive seals will use more oil. They only work good if the valve guides are new.

I have umbrella seals now and it burns oil at idle (while driving its fine - no smoke, plugs are nice and clean).

Thats why I wanted to put positive seals on the intake valve stem just for now so I can tune my carbs a little better then when I rebuild the engine I'll get the valve guides done.

Does any one know of a positive valve seal that will fit A series heads? (a drop in replacement that requires no machining to the guide)

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Most likely, although there is a small possibility the rings are bad. Do a wet & dry test to tell for sure.

If it is the usual valve guide wear, then umbrella valve seals will clear up 80% of the problem, and do not require you to remove the head.

Were is the burnt oil coming from? If the engine is 'burning' oil, it's coming out the exhaust, which means you would most likely have an issue with your piston rings. A compression test is a good indication of how well things are sealed.

That's what I have now but on high vacuum situations my engine burns oil so I guess my valve guides are worn?

Those positive seal kind (stays on the valve guide) don't work too well when the guide gets a little worn.

And the O-ring type seals are only partially effective.

I recommend Ford-type "umbrella" seals on both intake and exhaust valves. These stay on the valve stem and go up/down with the valve.