How many amps would these things draw ?? Wondering what size relays would be needed for each. Rather than singles I'm liking the MSD solid state unit(s)

Headlights (each pair)
Electric fan
Electric water pump
Electric fuel pump
Horn
Starter solenoid
am I missing anything ??

Thanks

There is no easy answer as they are going to vary by MFR.
But 50 to 100A SHOULD cover all excluding the fuel pump and horns which 20-30 A should safely do. Also Higher amp relays than what is actually needed is good for longevity Some fans are also current hogs

Contact the owners of those businesses that make and sell those products and ask them how many Watts each one draws and do the math on Watts used for each circuit and go from their

Good prior to use questions.
Specification sheets you can look at before buying almost always list normal current.
Underwriters Laboratory tests are a source of maximum current before fire breaks out

Measuring current using a either a

10 amp multimeter
cheap digital 30 amp fuse checker
1 to 300 amp clamp around wire “Hall Effect” current meter

The cheap digital display fuse checkers are a good way to add DC current read out to battery chargers.

My youngest brother so liked my 6 year old USB voltage/current measuring dongle
that he ordered 4 newer whiz bang versions,
and gave 2 to me.
One of the new ones does far more: displays graphs, watt-hours, and milliamp-hours. It also has Type C and Mini USB inlets and outlets

Don’t fall behind.
Keep up with
“Current Affairs.

10A multimeter isn't going to cut it. the Derale fan i put on my 51 draws about 17A on low speed, 25A on high speed.

You can look at the recommended fuse ratings for your specific item and get a relay rated more than the fuse. For example, a generic low pressure carb fuel pump will draw much less than an EFI style pump.
Headlights are really going to depend on what type bulb you are running as well. An LED bulb will draw substantially less current than incandescent or halogen bulbs. But generally speaking a quality (Bosch for example) 30A relay will cover everything you need. Speaking of which, not sure why you want a relay for the starter solenoid, it already has one, it's called the starter relay as does the horn, it's called a horn relay.

Need to keep in mind where your battery will be located also.

Because they're fugly ancient technology. I want neat and tidy.

The Mopar starter relay is stinkin' ugly. Unless you're doing a restoration, I see no reason to not replace it with a modern piece.

And the horn relay is the same !!

True on both, but they were well designed and functional. Modern stuff can be dicey these days unless one spends the $$. If you're doing a complete rewire have you thought about just moving them elsewhere? I've always liked the accessibility of the starter relay for running valves etc. I've hidden a few in small black plastic boxes with flip covers for access