I'm running a 427 side oiler with a flat tappet Comp Cams 292S. Good lumpy idle, pulls nicely from 2000 rpm, loves my 3:31 rear gear ratio. 2X4 intake with 600 cfm carbs. Perfect match for me! 10.5 to 1 should be fine with alloy heads, I'm running 9.8 to 1 with iron heads. The 292S tops out around 6200 rpm, enough rpm for me! I went with a 'kit' which is highly recommended no matter WHAT cam you get. Get matching lifters, springs, etc. In my case I also went with new valve retainer kit as well. And SHIMS to set correct valve installed height.
BREAK IN is very important with a new flat tappet cam and the new EPA mandated engine oils which are MISSING key ingredients we USE to have. These new engine oils DO NOT provide sufficient
oil protection and during break in you MUST use certain additives. As well you should remove the INNER valve spring for break in and re-install afterward.
Yup, no doubt those forged pistons saved your motor! I went with custom forged pistons myself, thats one area I just didn't want to cut corners on. Use new spiral locks for the wrist pins. You might consider 'custom pistons' if you want to add 'quench' or get that 'perfect' compression ratio based on your combustion chamber size. For both of those reasons (nailing the perfect compression ratio AND adding quench) is why I went with custom slugs. Stock 428's basically have no 'quench', you need to know for sure the CC of the heads to calculate compression ratio.
See my engine blog for more detail on cam breakin and
oil additives, a MUST for flat tappet cams.