Honda-SOHC

So, I finally decided to trip up a 400 four engine. they are selling 460cc pistons online for about £150, cant afford yoshimura
Bought some spare barrels with 0.5 oversized pistons.
When it arrived the pistons wont slip in the barrels??? I pondered and saw the pistons have the following markings:
POP Y
CB450F
on the top it has 0.5 and a E for the exhaust valve.
The recesses for the valves are bigger than standard and the top looks "fuller"

These are the Yoshimura ones right? has anyone seen these... in the flesh as it were?
I understand Yoshimura did 54mm and 54.5mm bore and presume the ones I have are 54.5mm because of the 0.5mm?
Can anyone confirm this?
They measure about 54mm but its hard to tell with a ruler.
I have 4 pistons with intact ring sets.... can I just get a rebore and chuck em in ... using a different head gasket
will I need different size con rods with different sized little ends?

I needed to replace my crank, one of the journals was shot with a groove for the oil way. very poor.
I bought a crank off ebay and has no wear or none that I can see even the typical banding where the oil way goes is just noticeable. I have the bearings from the crank and they are only showing very slight wear so all in all I was lucky and its all tip top. the bearings are all jumbled up and I don't have the codes for the cases the crank came from.

My Crank case codes are BBBAA (the cases I am going to use)
Crank numbers are 11111
manual states Green for the BBB
and Yellow for the AA

I cant get any yellow shells
Question, does anyone know where I can get some yellow shells from
Question, will it matter if I put green in throughout, I assume 2 of the bearings will be tight but will it matter.

I was very reliably informed that it shouldn't matter if I run it in carefully but logic suggests that I am doing something fundamentally wrong, but I am running out of options.
I have spoken to crank grinders to remove 0.01mm off the two journals but they don't want to touch it.
It seems insane to try to ream out the cases so I have BBBBB across the whole series of bearings

Any advice

I have a standard exhaust, solid enough but looks a bit tatty.
I took it to my chromer and he told me he couldn't do the collection box and two pipes due to the shape and complexity, burbled on about anodes and he wouldn't be happy with the quality of the job.

anyone managed to get some pipes re-chromed without any problems? and where? hopefully Yorkshire area but will post if necessary.

Hi Guys,
Anyone know where to get new metal swinging arm bushes for a 400/4. I seem to recall bronze are preferable??
Any advice welcome... type and supplier.