Is there some good reason you want to do this? Such as the car running poorly or vaporlocking or something?

If you are wanting just cooler, denser air for more performance, I don't think you'll notice any difference regardless of what you do. Since your 1800 has no belly pan, there's quite a bit of outside air circulating around in there.

That said.. yea. If you must, an ugly black plastic 'box' air cleaner from a 140 or early 164 would be what you want.

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-Matt I ♥ my ♂