SO that means the old school Briggies with the exposed spinning top and side starter, around since the 50's, is a good one.
The 50s was quite a good era for enduring engine design. Ford's Windsor V8 and the Buick V6 to name a couple.
Well, nope; the alloy block/alloy cylinder bore ['KOOL BORE', in Briggs-speak] Briggs engines first came out in the early 1960's, IIRC. As did their first vertical-shaft engines. I'm sure CyberJack will know for sure.
See further the excerpts from 'The History of Briggs & Stratton Corporation' (Form no. G-8751-4/89) page 7 below:
"In 1948, The Briggs & Stratton Engineering Department, with Leo Lechtenberg having responsibility for the project, requested permission to begin work on a die cast aluminium engine to meet the need for a lightweight, four cycle engine for the small rotary lawn mower"
"The chrome plated pistons were tested successfully in cast iron engines with aluminium alloy cylinder sleeves, in sand cast aluminium alloy liners and finally in 1,000 pre-production sand cast prototypes before the Briggs & Stratton aluminium die cast engine was introduced in July 1953"
A newer PDF of Briggs & Stratton's history 'CELEBRATING OUR FIRST 100 YEARS THE HISTORY OF BRIGGS & STRATTON' (MS-8751A-11/07) is downloadable off the internet.