Oil drian holes plugged Ht4100

[old fatty]

Hello,

I purchased an 84 Sedan deville with 87,000 aprox miles. I noticed that it had a severe oil leak around the valve covers. I pulled the covers with new gaskets in hand. When I removed the covers oil poured out over the exhaust manifolds and on the ground. So I thought well no big deal I'll just declog the drain holes in short order and get my car back on the road. That's when I discovered only two drain holes in each head that routes the returning oil around the head bolts. Hmmmm. Now this is a challenge. Am I safe to pull the head bolts and clean the passages or will I strip the aluminum? Or better yet is there a better way?

old fatty