1965 300 build-up questions

[es2rider]

Hi, I'm finishing a frame up restoration on my 65 F100 short bed 2wd. It will just be a weekend fun truck, no heavy pulling loads
and no street light racing.
I am rebuilding the stock 240 into a 300. I believe it is the original motor, it has the "C5***" block #s.
I read in another post concerning the early blocks have a smaller thrust face on #5 main bearing insert.
How do I determine if this is an early or later version.
The article stated to check block for thrust bearing size???
If I determine that it is a early block, will I need an "early bearing" kit and if I use a later 300 crank will it be a problem?
So many questions... sorry

I am using the following parts for the build up:
Keith Black Hypereutectic Pistons .030 over
COMP Cams K66-237-4 -COMP Cams High Energy Cam and Lifter Kit
Harland Sharp S4002-7 roller rockers
ARP hardware: rod, mains and head
Offy C intake, no carb yet
EFI manifolds

The KB pistons have a 0.215 inch deep, 2.700 inch diameter recessed head with 0.055 inch quench step.
I'm not sure what the compression ratio will be with the 240 heads.
I want to be sure I can use pump gas though I wouldn't mind if I had to use premium.
My machinist is suppling the all rotating parts (crank, rods)
Thanks in advance for any help.

[CNC-Dude]

It will be more reliable to measure the size of the machined thrust in the cap and block than to try and go by the casting #'s, as this is never an absolute method, and there is always an exception to the parts book it seems. Also make sure that the crank and block are for the same thrust size, and not one of each, since it always seems someone has been into the engine before and mixed and matched parts.

[THE FRENCHTOWN FLYER]

Replace the 240 damper with a 300 damper as it is "tuned" to the longer stroke.

[es2rider]

I have ordered a set of Std. main crank bearings to compare with what I have in the block now. I ordered for a 1970.
I'm hoping this will let me determine if I have an early or late style block.
I figure that if the new #5 thrust bearing measures up the same as the one in the block now I have the newer style block and I can use a rotating assembly for 1970.
Does this sound right?
I have nothing else to compare.
Thanks

[es2rider]

So I took my bare block to the machine shop and had the engine builder/machinist check it out. They specialize in Big Cubic Inch high performance offshore marine engines. BIG $$$...
Turns out the shop had done 300 Six engines for several years for UPS.
He has done several 240/300 conversions and was familiar with the early smaller thrust face on #5 main bearing insert, and says its not a problem, just a little machine work. He said that was a common running change on some Dodge and Pontiac motors also.
He had everything in stock to to get the job done.
Thanks again for the help.

[mutt]

Cool, man. Nothin like a machinist who knows your motor.....keep us posted & try for pics-