Few questions .Weekend build 318,with magnum heads

Sorry for the long post to follow but there is a lot to cover...

We just had a thread here recently with someone with Magnum heads suffering a broken spring with the stock springs. It was with an xe268-like cam. Turns out the springs were getting veeery close to binding and one broke. Here is the thread; it has the new springs chosen listed later in the thread.
Top end popping noise

BTW, you do know that the oiling to the Magnum rockers is up through the pushrods? That is totally different than your LA rocker shaft oiling. So you need the AMC type lifters and oil-through pushrods.

If this is a daily driver, then I would not hesitate to go with the Magnum heads when putting in a cam. You seem to know that the 318's suffer from low compression out-of-the-box, and for pure driving around, good low end torque is the way to go. And, it'll work better with your stock torque converter.

I'll give you a reality check however; the 268 cam is gonna be too big for daily driving, for your compression ratio even with the Magnum heads unless you have the flat top 318 pistons, and even then, it is gonna be marginal IMHO. Do you know the pistons inside the engine? Is there any way to borrow a bore scope and look in and see if the piston tops have 4 valve reliefs? It very likely has the lower compression pistons with the 4 valve reliefs, but the CR numbers work out significantly different so it would be good to know. OR, take cranking compression readings and report those.

It all depends on if you like driving an engine that bogs at low RPM's for a daily driver, and so that is why I ask. I have run some numbers on a typical 318 LA bottom end with the Magnum heads and the thinnest head gaskets (Mr Gasket 1121G) and the XE 268 cam, and the DCR (dynamic CR) works out to be in the mid 6-ish range. That is a bit lower than with the stock cam and heads, so it is a 100% mistake to think that the low RPM performance will be any better with that cam. If you are keeping the stock torque converter, then if you push hard on the gas from a dead stop, it will bog....bog...bog and then finally take off.

Please consider a smaller cam like the 256 range. Stick with the XE or Voodoo type of cams so you can get the best lift to duration ratio. I personally like the 112 degree LSA of the Voodoo 10200701 or you could go with the XE256. And with the 1.6 Magnum rocker ratio, either of these cams will have THE SAME lift than the XE268 with the 1.5 LA rocker ratio. So you are not losing lift here, just helping your low end torque in the type of driving where low RPM torque is important to have.

And I agree with the goal to save $$, but you might also want to consider milling the heads .030" or so. Anything to help DCR....I'd also suggest the Mancini MRE262 chain set (or similar) so you can advance the cam timing 4 degrees.

Using the xe256 cam, milling the heads .030", and advancing the cam 4 degrees (for a total of 8 degrees cam advance with that cam's 4 degrees of ground-in advance) to get the ICL to 102 will get you up to a DCR of 7.25; that is a lot better. Not quite a tire frying monster but it will have more kick than stock at low RPM's. The smaller cam will also help your fuel economy, and with the top end parts will work fine well past 5000 RPM.

Then work on the ignition timing and mechanical advance and I think you'll really be pleased.

BTW, your carb size is nice for this, IMHO.