Thanks everybody for the feedback.
The consensus appears to be to change and follow Debian's usage of pristine-tar.
I have updated the Maintainers Packaging Guide[1] to reflect this.
I have updated the Jenkins buildscript[2] to support this.
I am testing an update to d1src-merge(1) in devscripts-devuan to support this.
The change can only happen gradually as new upstream versions appear. Existing
orig tarballs cannot be altered.
Mark
[1]
https://git.devuan.org/devuan/documentation/src/branch/master/maintainers/PackagingGuide.md#debian-gbp-conf
[2]
https://git.devuan.org/devuan/package-pipeline/commit/f45d0ab24f0274628001c72406e3c9ed6aaf72af