Id like to say no but i cant cause iv never had it tested, however i have had a few heads milled before a couldnt tell any difference in power curve. if it does it wont be enuf that you will ever be able to tell. Id just go with the same cam you were planning on.. btw i have about the same cam in my ls1 with a .030 mill and the valves just barly cleared so i fly cut my pistons .020 to be safe.

 

Short answer: Yes. Milling will affect flow numbers, typically decreasing them. I say typically, because I have never seen them increase the flow numbers on the bench, but I cannot say 100% certainly that it could not happen.

 

if your trying to find the answer of why the numbers were so different, although I did not see how much you seen, but you might want to know two questions from the 2 places. What kind of flowbench and what bore size did they flow it with. Benches will greatly differ from manufactures, but flow pretty consistent on the same bench. I know my SuperFlow flows 5-7 cfm less then the test bench at SuperFlow. And they told me it's typical to be within a percent.

There is also 10-15cfm on a LS with a good clay orifice. If the second did not use one, you would see a decrease in flow.

 

These are the flow tests: Original

.100 .200 .300 .400 .500 .550 .600
int.cfm 74 131 186 233 267 278 290
exh cfm 60 107 143 178 202 210 216

After milling
.200 .300 .400 .500 .600
int cfm 114 163 214 245 273
exh cfm 88 121 150 172 185

difference
.200 .300 .400 .500 .600
int 17 23 19 22 17
exh 19 22 28 30 31

I got a cam spec'd on the original one, since I wasn't sure which one to use. The cam specs at 226/230* .598/.600"
on 113+2 LSA. Hope it does ok I don't think there's that much difference.