[Jay S]

I am going to suggest a couple different directions than what has been suggested.

If you are wanting to rod stock cast rods, I would absolutely stick with a stock type pressed fit speedpro L2262F piston. No rebalancing, works perfect with your rods, and way cheaper than the other aftermarket options.

Next your probably think that puts my compression to high, I calculate it to be 9.8:1 if it has 72 cc heads, with a .045” thick head gasket, 6.7 cc valve reliefs and the piston down .020” from the deck. Plus I think your engine has big cylinder scallops, so it is probably closer to 9.7 SCR all said and done.

You most certainly will get the argument the 9.7 is to high for 89 octane. But there are ways to manage it. I run 11.2:1 on 91 octane on my iron head Pontiac, I currently do not even have a Pontiac with less than 10:1 compression, at 9.7 to 10.5:1 compression we are running 87 octane, and all 455 cid or larger engines, which are more prone to preignition than your 400.

When you drop the compression a point down to high 8s your really hurting the efficiency of the engine. Which is ok, there is nothing wrong dropping the compression to meet conservative fuel octanes, the 068 regrind would like to be around 9:1 for what your goals described.. Lowering the compression is not always necessary though, sometimes you can design the engine to manage it better. It depends on what your willing to change to get there.

At 9.7 compression, I would use a Summit 2802 camshaft, 224* intake, 234* exh, .465” and .487” lift, 114 LSA, degreed in at 109* or 110*. If you kept with the stock 2.11” 30* intake valve it would run on 91 octane. If I was building it, I would actually change out the 30* intake valve to a 45* intake valve, it will make less peak tq and a little less power than the 30*s valve, but at low end cruising it will make more power, and be more efficient and get a few mpg better with your overdrive. It will also seat the intake valve a little deeper and gain a couple cc on the heads. That combination will knock the VE down at your peak tq, and spread the power out more. That simple change on the valve angle is like widening the LSA of that summit cam to 116 from 114, and it would end up dropping the octane requirement of the engine down a few points. With some port work and headers, it would actually run on 87 octane fine. With stock ports and manifold it probably would not quite get there, but it would be noticeably more tolerant to fuel than if it retained the 30* valves. I run one of my cars on 87 octane that has iron heads and 10.5:1 compression with over 500 cubes.

For lifters I would either search for NOS HFT lifters, old stock from the 80s Johnson lifters, have your old lifters machined and resurfaced, or buy new Hylift Johnson lifters which often run just under $200 now. Butler sells them. My first pick is NOS lifters or a old set of NOS Johnson’s.

Keeping the compression higher by close to a point the engine will make more power and be more efficient than it would be with light weight internals and a point lower compression. My 11.2 compression iron head combo makes a lot of power (550+), sports the factory q jet, looks stock except it has headers and get’s around 20MPG with 3.23s and no overdrive. For your exhaust, honestly, you have a huge hurdle finding anything but log manifolds for a 67.