Migrating Time Machine to a new disk

[Irl]

My old (2009, 1 TB) external HD is showing signs of needing to be replaced. It is partitioned (GUID Partition Map) into an 800 GB APFS container with several volumes on it and a 200GB Mac OS Extended (Journaled) partition (MBTMach) used by Time Machine. I want to migrate to a new drive and retain the Time Machine backups. I propose to do this as follows; please comment!

Partition the new drive similarly to the old including a Mac OS Extended (Journaled) partition MBTNew
Turn off T M
Rename MBTMach to MBTOld
Use SD! (in restore mode, right?) to copy MBTOld to MBTNew.
Dismount MBTOld and rename MBTNew to MBTMach.
Then turn T M back on.

Will this work? Anything I should beware of?
The new drive will be connected directly to one of the USB-C ports on my MacBook and the old one (which is Firewire 800) to a different port using a couple adaptors (USB-C to Thunderbolt 2, TB 2 to Firewire). MBTMach currently has about 100GB of data, so I'm anticipating about 20 minutes for the transfer (since the FireWire will presumably be the bottleneck).
Do I have to do anything about indexing? I have told Spotlight to not index MBTMach and plan to keep it that way.

[dnanian]

You'll use "Backup - all files", not "Restore - all files", to copy a Time Machine volume. "Restore - all files" specifically ignores Time Machine backups.

It's likely going to take longer than 20 minutes. I also don't think renaming will do it: you'll need to specifically select the new drive as a destination. It'll do a lot of preparing but should retain the info.

[Irl]

Thanks, Dave! It's working now and looks good so far. You're right about the 20 minutes -- looks like more than an hour (there are about a million files, which was a surprise to me -- I had never looked in detail at the Time Machine volume).
Tidbit: To get the external drive to start up (upon plugging in, its front panel light would flash briefly and nothing else would happen) I tried giving a rotational bump (nothing), then heating it to about 120°F (nothing), and then cooling it to about 50°F (worked!). This is a nine year-old Western Digital MyBook (which had often been a little quirky on startup, but this seemed like a hardware failure -- wouldn't spin up).

[dnanian]

Glad to hear it!