383 cam choices

[torqueflite]

I need some advice on the combination I currently have in my 70 SE.
383 bored 20 over. performer rpm air gap. 670 Holley. headers.
Not sure on the compression, the pistons look like like KB's with very shallow valve reliefs, they come up level with the top of the block, 040 felpro head gaskets so I reckon around 9.7:1?
Cam is Isky 270 Mega  221@050 , .465 lift ,  108 lobe centre ,
Compcams 911 valve springs, crane adjustable rockers, 3/8 pushrods
3.23 rear end with  275/60/15
Mopar dizzy   running 18 initial 38 all up
Not sure what the converter stall is ,
Ive done just over 2000 miles on the motor, and while it goes real well when you rev it out, but I'd like a bit more in the bottom end and hopefully get a better quality idle.
I think I need to change the cam and maybe get some smaller dia back tyres [ I don't really want to change the diff ratio if I can help it ]
Either an Engle K56  224@050. 504 lift. 110 lobe centre . Or a hughes HEH1928BL  219/228@050. 489/524 lift. 111 lobe centre
Do you think I would get any improvement going with a wider lobe centre and more lift. which one should I choose ?, or is there something better suited for me.
Also wondering about the extra lift these cams have, I don't really want to take the heads off to check the clearance between the valve and piston if someone can tell me for sure it will be OK.
And another question about the cams, would either be OK for a six pack set up in the future ?
Any advice much appreciated.