Get one with replaceable attachments then you can at least add things to it to do what you want to do, either a clock or a modified anvil.
Mechanical Measuring tools much like Electrical measurement has its Brands, Linear/Unbranded are your £2.99 meters, Moore and Wright are your amprobes, Mitutoyo is akin to Fluke, if you want 8.5digit sadness then look up Tesa Microhite stuff, or even SIP205M.
Typically they will measure 150mm plus a little extra. It will take into account the size of the head.
I suggest looking for a little granite surface plate as well, its a very good surface to measure on.