help with a Marine flathead

I have a '51 Chrysler Marine 265 cu.in. 6 cyl. in rebuild. It is model M47S, with two Zenith carbs. I'm going to change to electronic ignition, and my machinist thinks I should consider a new coil, plugs, carb jets, and shaving a bit off the head... Sounds like fun, but I don't know where to turn to find someone with experience in this area. Can anyone here give me an opinion on making these mods? The engine was rated at 135 HP, and more power is always better, in my mind...
Thanks for your time, Grant in VT

Thanks for replying. There isn't a way to put a header on - the engine sits under a so-called "dog house" that just fits, and the restoration would be messed up if I changed it. Besides, the Intake/Exhaust manifold is a very nice copper structure...
Most boat guys are very concerned with authenticity for the boat show circuit; I just want my boat to run at its best. I think you hot rodders are the guys who understand this best. I hope I can find someone who's had experience with the Chrysler L-head.
Thanks, Grant in VT

I think that you have a Chrysler Grey Marine engine. Your machinist sounds like he's on the ball to me. Just do the math and watch the valves. A little cam would help with the increase in compression. Everything else should be by the book.
You might even find a aluminum hi compression head, a few were cast.