WAY
Key=420 m

WAY 2
Key=420m

WAY 3
Key=420

WAY 4
Key=420ft 

<<<lines>>>

Key=* {
	set key2='${Key|subst:"[ \t]*~>" | subst:"(?<=[0-9]+)$~>m"}';
	set key3='${Key|subst:"[a-z]+~>"}';
}

key2 ~ '.*m' { set key3='${key3|conv:"m=>ft"}'; }

Key=* [0x2]

<finalize>
Key=* {name 'key2=${key2} key3=${key3}'}