I'm with Bob!
The larger wheels, when the trailer is finished, will look very good.
Many people choose the smaller wheels (usually by default) that come with the kit trailers.
Nothing wrong with them, but the tiny wheels usually look way out of proportion...
The springs you have look ancient, not a bad thing, as long multi leaf springs ride great.
They are very rusty though, and should be taken apart, de-rusted, and inspected, cleaned, painted, and in my opinion, greased.
The difference in the ride between dirty/rusty and cleaned/greased is like night and day!
Nice looking platform to build on, good luck with your project!
Rob
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...