In the 1967 set, Topps assigned #400 to his card, one of the "superstar" numbers (ending in "00"). The others were:
100 - Frank Robinson
200 - Mickey Mantle
300 - Willie Mays
400 - Bob Clemente
500 - Juan Marichal
600 - Brooks Robinson
In addition to the "00" number status, each player had their "floating head" appear on the checklist containing their base card. (Jim Kaat appeared on the 4th series checklist. Maybe his card number was 350?)
Roberto Clemente was playing ball in Puerto Rico when the Brooklyn Dodgers signed him, and sent him to their AAA team in Montreal. After 1 season as a bench player, the Pirates selected him in the Rule 5 draft, and the rest is history.
After the 1958 season, Clemente joined the US Marine Corps Reserve. His 6-month stint in basic training was credited with improving Roberto's strength and conditioning (which had been affected by a car accident during his rookie season).
Clemente and the Pirates won the World Series in 1960. That year he began a string of 6 consecutive seasons as an all-star. Roberto led the NL in batting during the '61, '64, '65, and '67 seasons, and won the MVP award in 1966.
In 1968, his batting average dipped to .291, which would be his only season under .300 (and only all-star absence) after 1959. He bounced back with 4 more "Clemente" seasons.
Roberto led his team to a World Series victory in 1971, and collected his 3000th hit in the next-to-last game of his final season (1972).
He was 38 when his plane crashed off the coast of Puerto Rico, en route to Nicaragua on a humanitarian mission on 12/31/1972.
Also check out Clemente's 1970 card.