318 build
Well I wasn't gonna put my 2 cents into this hodge-podge, but since it's gone off the rails anyway; here goes.
Start a new thread cuz there is almost nothing in this thread worthy of being called good advise; and nobody actually tried to answer your question, with the exception of the one guy everybody likes to pick on.
I've given my opinion on a few 318 builds, and also got bashed, so no sense in me going thru that again.
Ryan, there are quite a few smart guys on this forum, smarter and more experienced than me. But there is also a preponderance of testosterone here, and a lotta herd-mentality.
Lemmee say this, which is based on my 50 plus years of experience;
1) the smallest difference between your 318 and a 340, is the bore size.
2) the biggest difference between them is the cylinder pressure.
3) and the 340 cam was a good cam in it's day, now 50 years ago.
4) with a manual trans, your engine is as good as married to the driveshaft, which is married to the rear gears. What you do to your engine has to be married to what the wheels are doing. If you miss the mark, you will not be happy.
5) if you install the big port heads, do it for a good reason.
6) never pick the cam first, unless your pockets are deep enough to make all the changes that may be required to run that cam. and
for crying out loud, when you refer to a cam, do so by it's 050 specs and include the LSA. From those numbers, we can generate everything we need to know about how it's gonna run. I think it's not fair that I have to go looking for those specs, knowing only a lift, and none of the smart guys can give good advise until the cam specs are known.
7) as others have asked, state what you expect out of your engine. For example, saying that your car has 3.23s and you want to keep them, is gonna throw out about 80 percent of the street cams available. and for a manual-trans 318, probably more.
8) state what fuel you are willing to pay for. Each octane gas has a pressure ceiling, beyond which the engine can get into trouble real quick. You can run less pressure than that ceiling, that's ok, but not more. and each octane build then, for optimum performance, is a different build.
And until your exact Compression ratio has been calculated, and your quench has been established, nobody can give you good advice, unless they include all the requirements that apply to that advice.
For example, if your pistons are .057 in the hole and your heads have 72cc combustion chambers , there's gonna be hundreds of dollars need to be spent to run a stock 340 cam, and to not have a dog every time your rpm falls below 3000 rpm.
So you know, one guy can tell you his 284cammed 318 with 340 heads was a giant killer, because from 4500 to 6000, and it was.
And another can tell you that his 340 headed and 340cammed, 318 was a dog with 3.23s, and it was.
And I can tell you that a first gen 340 , with 318heads, a 318 cam, and 2.94s with a bit of stall was a killer combo, and it was.
9) Nobody wants to admit that every good combo is very highly tied to cylinder pressure. Two identical engines, other than one cranks 130 and the other cranks 185, these are night and day different engines. I'm not kidding. Not only is the one close to twice as powerful, absolute; but the midrange is killer fun, and from idle to 3000, you would never know that it was just the same basic engine as the 130psi example.
Pressure makes heat. Heat makes torque. Torque times rpm makes Power.
The more pressure you have, when you need it, the more fun your engine/combo will be. and when it never comes, Ryan is a sad sad guy.
10) with a manual trans, it's very easy to make a low-pressure doggy streeter, that can only be band-aided by gears and/or slipping the clutch. Don't be a statistic.
11) now;
I did not tell you what heads to run.
I did not tell you what cam to run.
I did not tell you what cylinder pressure to run.
I did not in any way answer any of your questions.
Decide for yourself what good advice is.
Now, go read what @Dan the man said.