I do not sprint or train for sprinting but for those who do maybe this might be of interest??? 
found an article by Borzov that said “Starting positions have for some time been defined by the placement of the starting blocks and their distance from the starting line. For just as long there has been controversy concerning which start----the “bullet” (bunch), “bullet” (stretched out), or “conventional”—is the most effective.The start or starting positons for each sprinter is determined in accordance with his anthropometrical data. However, long -term observations of top national and international show that at times the same start is used by athletes who have totally different body dimensions. At the same time some athletes of identical height and leg strength use different starting positons. Studies on this topic have shown that the leading sprinter, in spite of having different body proportions have similar angles of flexion in the primary body segments. This similarity suggests that it is possible to establish an optimal staring positon model. In order to determine this model it was first necessary to find the optimal angles between the primary body segments and then establish the starting position in accord with them. Maintaining optimal starting position angles provides the sprinter with the fastest start out of the blocks. Our study encompassed a group of the top Soviet sprinter in recent history. According to our data in spite of the differing heights of the athletes in the group (from 165cm to 183cm), the angular values are of similar magnitude in most cases. This substantiates the presence which can be represented as shown in the illustration and table:
These angular values can be used to design an optimal starting position. Similarity of angular values is possible in the presence of different block placements which, in turn depend on the individual sprinter’s body. Hence, when teaching starting technique to beginning runners we recommend the use of a straightedge (ruler) positioned at the athlete’s center of mass. Using a protractor, position the athlete’s body in accord with optimal angles of flexion in the primary body segments , and then “place” the starting blocks “under” him. This provides the beginning sprinter with prerequisites for the most effective and fastest start at the very beginning of his training.”
**I drew this sprinter myself so I apologize ……but this is what the article shows as the
the numers are in this order
Angles/Degrees(Average)/ Variation range
B / 104 / 98-112
A1/ 100/ 92-105
A2/129/ 115-138
M1/21/19-23
M2/13/8-17
Note: Angle B : between the sprinter’s trunk and a vertical line drawn through the center of mass.
Angle A1: between thigh and shin of forward leg
Angle A2: between thigh amd shin of rear leg.
Angle M1: between the thigh of the forward leg and the vertical .
Angle M2: between the thigh of the rear leg and the vertical
Not sure about these numbers but for those who are not a gimp like me maybe these make sense…Peace! 