Back In Action - With Questions

[rn2fine]

Greetings Everyone,

I hope all is well. I have not posted in a while. Went overseas last year and have been trying to catch up with life since I got back to the states. I have pretty much finished up my 72 Burb (pic attached) and am moving on to two more Chevy projects, a 68 Chevelle for my wife and a 70 C20 for my daughter. I have a few questions for some of you experienced mechanics out there. See below:

1) My 72 Burb has a late 90s based 350 with Edelbrock RPM heads and an Edelbrock EPS manifold. Where the manifold meets the bllock at the front of the engine I used Black RTV per the manufacturers instructions. The area of the RTV keeps getting dirty/greasy and when I spoke to a friend he said that a small amount of engine oil is probably weeping from that area. I clean it off and 2000 miles later its all dirty and greasy again. Has anyone else experienced this?

2) I am about to rebuild a late 60s 307 and have been looking for some really good valves for the stock heads. They take a 1.720 intake and a 1.50 exhaust. Manley carries some severe duty valves that I would like to get but the 1.720 only comes in a +.100 length. Is it OK to use a +.100 length and should I get an exhaust valve that is also +.100 in length so that they are the same? Will I need to get longer pushrods? I plan on using roller rockers and a mild performance hydraulic camshaft.

Thanks,

Jeff