On the surface, the biggest problem with your combo is your compression ratio. Typically the 87cc heads are used for a 455 or larger engine. Here is a calculator you can use to determine the compression ratio.
http://www.wallaceracing.com/cr_test2.php
This is what I came up with:
Your displacement is 404.04 CID
The Compression Ratio is: 8.86
For an aluminum headed engine, I would want closer to 10 or 10.5-1 compression ratio. The RA IV cam would be a great choice if you had more compression. With what you have, you would have very little lower rpm power. I would choose the Crower cam if you were to run the lower compression.
I see two other options. First is to obtain a cylinder head with 72cc chambers. The second is to obtain a stroker crank. (4.21 stroke) Either of these options will get you to 10:1 compression and then the Comp Cam would be a great choice.
JMO