My 1991 chevy small-block305has centre bold valve covers.
If that helps.

 

87 was when the center bolt valve covers were introduced. Also when you see the center bolt valve covers that is a good indication that the center bolts for the intake manifold are at different angles than the rest if that helps

 

The short block doesn't matter however, you can use center bolt heads on a 54-86 block, and vice versa. Only thing that really is going to matter is the fact that the intake bolts are at a different angles, limiting your choice of intakes and heads for whichever you choose, as mike said

 

My goal for this engine is some what fuel efficient and with at lest double the HP I have now (stock TBI 305, 174HP) So Im going to start witha ZZ4 short block with edelbrock cam, lifters, push rods, heads, TBI intake everything I can get for the engine then get what ever is left from other performance part places.

What do you guys think of that? Good bad?

(Didnt see the second page of posts) Ok So ya see dumb question then heh Thanks That makes sense now I'm basing everything around the TBI unit so Im using the TBI intake manifold from Edelbrock which means I have to use the right cam system for the right flow along with the right valve system so Im just going to change the heads as well. So in short new short block to make it simpler and cuz I want a 350

 

For the short block if you are not planning on building one, I would suggest this one:
http://www.jegs.com/p/Blueprint+Engines/761058/10002/-1

Would be a great base for around 300-350 horsepower.

Valve train wise: I don't recommend going with edelbrock components, the kits they use are pretty generic spec wise and aren't matched well to your application. Figure out what the rest of the components are going to be, then fill out a cam request from comp cams.

 

Hmm, damn I'm still kinda new to engine building like that So I'm not entirely sure what to go with honestly Then engine is already picked tho the cam and stuff has always kinda lost be besides how they work.

 

Like I said, go to compcams.com and fill out a cam request. Are you planning on going solid, roller, or flat tappet?

 

Hmm Then the question that pops up in my mine is, which would be best for a reliable and lasting enginethats pushing at the lest 300HP

 

If the block is machined for a roller cam you can go that route for less friction. But either way you may want hydraulic lifters for the zero maintanance.

 

Hydraulic roller is the way to go, nothing wrong with flat tappet though.