Vacummn leak at block halves on 35 hp Johnson.

[flintcreek]

1981 Johnson 35 hp electric start. I have had problems getting it to run, confirmed running out of gas. First off figured out it was sucking air at the intake gaskets, removed resurfaced the gasket surfaces and reinstalled. It appears this leak is now fixed. Now the motor runs just a little better, but still not right and going dead. So with my sons help we spray the motor down with carb cleaner, starting with intake area and carb area no change in how it runs. Then we move back to the bypass covers and spray it down, no change. Then while I keep it running getting on and off the choke my son sprays down the joint between the halves of the motor on the bypass plate side and the motor smooths out. I can quit choking every 15 seconds and it will stay running when you spray carb cleaner at the joint between the halves of the motor. So right now it looks like I need to tear down the motor and reseal the halves. Any advice before I get started. I do have a factory manual, for a 78 model 35 hp....from the parts break down the block is pretty much the same, lower unit and some stuff is different. What gasket sealers do I need? Any special tools needed? Has any one else seen this type of vacummn leak. I think I can do this without doing the head gasket, it is already new and without pulling the pistons. Any ideals or advice would be appreciated.
Flintcreek